#precalculus

1 messages · Page 312 of 1

obsidian monolithBOT
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Zyzzbrah

hasty belfry
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this is pre calc / trig functions ig

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so i solved it and got sin theta > 1/2

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and b/w 0 to 2pi there are 2 solutions which are pi/6 and 5pi/6

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$$ (0,π/6)∪(5π/6,2π)$$

obsidian monolithBOT
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Zyzzbrah

hasty belfry
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this is correct answer tho

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how can i represent it in this way?

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after finding out the solutions

hybrid bane
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Wait...

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Your theta in (0, 2pi) doesn't really make sense

hasty belfry
hasty belfry
hybrid bane
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Sure but you seem to be referring to a set but talking about the interval

hasty belfry
hybrid bane
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If you are trying to say theta is an element of the interval (0, 2pi) you need to say like it is on the left

hasty belfry
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thats what im saying the answer should be just [pi/6 and 5pi/6]

hybrid bane
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Then just write the solution set {pi/6,5pi/6}

hasty belfry
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i mean ik the correct answer

hybrid bane
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So what are the options?

hybrid bane
hasty belfry
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but fuck it

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i solved the question

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all that matters

hybrid bane
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,w solve 2sin(x)^2 -5sin(x) + 2 > 0, x between 0 and 2pi

hasty belfry
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  • 2
obsidian monolithBOT
hybrid bane
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Yeah it isn't only 2 solutions is probably why

hasty belfry
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anyway thx

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for taking ur time out

solar pagoda
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what do you algebraically? I am pretty sure that is the only to do it. sin(2x) = 2sin(x)cos(x) comes from sum identity for sin.

cinder briar
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what is the range 1/x

opal tree
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What is the horizontal asymptote of 1/x

cinder briar
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y=0

cinder briar
opal tree
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Yeah y ≠ 0

gentle vale
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wouldn't you use the quotient rule on that?

willow bear
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wym quotient rule

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nobody asked to find the derivative did they

gentle vale
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I've been doing derivatives all day nom stop lmao
It's just ingrained in my mind

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My bad

fringe fulcrum
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Hey guys

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I'm thinking about not taking Precalculus next year and studying on my own

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Does a good book cover all of this?

hasty belfry
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sin 2x= 2 sinx cos x

hasty belfry
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there are loads of good books tbh

hasty belfry
viscid thistle
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I'm having some trouble with approaching this situation. I just not sure ir it'd be possible to find the 77th term without it being so time consuming. I also don't know why exactly n is only less or equal to 3.

lofty sage
lofty sage
viscid thistle
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Oops, in my text, I meant to the if not I greater or equal to 3, but I understand why now.

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This sequence is basically repeating values of 4, 5, 3/2, 1/2, 1. From term 1 to 5. And those values repeat again from term 6 to 10. This mean that my 77th term would be 5, knowing that sequence repeats every 1-5 terms

viscid thistle
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Alright got it 👍, thanks for the help @lofty sage

loud tundra
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What's a good precalc book?

viral bolt
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precalc for dummies

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LMAOO

viscid thistle
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if u want it

loud tundra
cinder briar
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if i have a binomial expansion of (4-x)^1/2

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for what values x is the binomial expansion valid for

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is it mod x < 1/4 ?

willow bear
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no, it's |x| < 4.

last folio
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I need help with this question under pre calculus II

viscid thistle
last folio
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okay lemme try

uncut mulch
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squaring may generate extraneous solutions (especially since sin(x)-1 is non positive)

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so you'd need to be extra careful

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I'd actually recommend rearranging the equation to
sin(x)-cos(x) = 1
and apply harmonic trig identities to express the LHS in terms of a single trig function

last folio
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okay ,thnx.

viscid thistle
viscid thistle
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yeah that video is litterally the entire class let me see if I can find it and send it. The only problem is that its kinda short but for concepts you dont understand you can just review on youtube too

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at least as a review its pretty helpful in my opinion. I just took precalc this year and this video is pretty much the exact same

loud tundra
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Interesting. I’ll check it out. Thanks @viscid thistle

candid cloud
hushed sphinx
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That gives some of the solutions, but not all.

gloomy crater
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can someone help me with this?

willow bear
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have you made any progress so far?

gloomy crater
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nope, can't think of anything

willow bear
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have you ever done things with quadratic sequences before?

gloomy crater
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probably not

willow bear
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maybe the words "first differences" and "second differences" may ring a bell...

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there is still a way to do this if not

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let $u_r = Ar^2 + Br + C$ and either set up a system of equations directly involving the first three terms (hard) or do some nonsense involving first and second differences anyway (easier mechanically but harder conceptually)

obsidian monolithBOT
gloomy crater
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oh

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I think I got it

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thanks

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so I have to do
7=A+B+C
19=4A+2B+C
37=9A+3B+C
and find values right?

willow bear
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that works, yes.

gentle vale
# viscid thistle yeah that video is litterally the entire class let me see if I can find it and s...

https://tutorial.math.lamar.edu/
I like this website for learning calculus

remote quartz
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does anyone have a folder or something of a bunch of quick trig limits questions to practice identities etc

frank vine
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trig practice problems?

frigid holly
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this simplifies to x^2 - 0.5x, right?

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the textbook I'm using has this coefficient 2 in the solution and I'm just wondering if I'm taking some crazy pills and have failed to understand something critical

obsidian monolithBOT
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The following error occured while calculating:
Error: Undefined symbol x

frank vine
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frank vine
slate reef
frigid holly
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if (2x^2 + 3x - 2) = (x+2)(x-0.5), then why isn't
x(2x^2 + 3x - 2) = x(x+2)(x-0.5), but instead 2x(x+2)(x-0.5) ?

frank vine
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Have to take out the two

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That’s why

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If you want fully and rightly factored

slate reef
frank vine
slate reef
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its 2(x+2)(x-0.5)

frank vine
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Could also use synthetic division to divide numerator by denominator

frigid holly
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ah

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forgot that one specific part when factorizing with roots

frank vine
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Yep

slate reef
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yes

frigid holly
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shows that I've been practicing mostly with 2nd degree polynomials with the a-coefficient of 1 😄

slate reef
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yup

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I don't like when the a coeff is not 1 so I always divide everything by that

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so it becomes 1

frigid holly
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makes sense. I'm guessing that in this example, it wasn't divided by 2 since that way you can use the quadratic formula with nothing but integers

slate reef
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yeah most likely !!

noble trench
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gimme a sec to find it

remote quartz
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thank you

remote quartz
noble trench
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here ya go

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oh wait those are derivatives

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oops

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i misread your question

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ahhhhhh

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i mean derivatves are a type of limit so they're still good practice 😉

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one good limit problem i know is the following

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although its kind of well known

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find lim x--> 0 sin x/x

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and also another one

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find lim x--> (1-cos x)/x

remote quartz
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do you know anywhere i can find like a bunch of them? are there any folders online

remote quartz
frank vine
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Hmm zlib might have some books on it

noble trench
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this one has some (although probs not the most reputable lol)

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also this video has a bunch of them from orgochem tutor

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u can just do them before he does the sol

frank vine
noble trench
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and if u don't get it u can watch him go through it

frank vine
verbal pumice
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What do I google for this to find something to help me learn to solve it? I'm not understanding how my teacher is explaining it, to the point where I don't even know what to type in to find a video showing somebody solving this type of problem

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I get that it's the difference quotient, and I know it, but I don't understand how to plug in the given interval in or anything like that

frank vine
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Search up diff quotient on YouTube I guess

calm fern
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integration of 1/(x-1)^3/5 (x-2)^7/5 dx

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help this question is making me feel like dying

gentle vale
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isn't the average rate of change from k(5.5) and k(12) just the slope between those points?

last wasp
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i think so

willow bear
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it is $\frac{k(12) - k(5.5)}{12 - 5.5}$, and everything needed to know to calculate this is given in the problem

obsidian monolithBOT
unborn yacht
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I'm out of school and haven't taken a college math class yet, so I'm not even sure if this is exactly the right channel. Dot products were never brought up, so I'm absolutely stumped by them. I'm trying to figure out machine learning right now, and this is one of the steps. From my understanding and 2 days of Google searches, the dot product is just a way of multiplying two matrices?

So I'm supposed to be getting the dot product of these two matrices, but what I'm not understanding is why. According to a Khan Academy video, the dot product is a human construct and was chosen pretty arbitrarily as the standard. But how does that work? I understand how to get a dot product, but I can't find anything about what the dot product actually represents compared to elementwise multiplication

And I'm just more confused, because the dot product exists for both vectors and matrices? It represents the distance between two vectors, so how does that relate to a matrix?

hushed sphinx
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Terminology: What your screenshots speak about are matrix products, which are not usually called "dot product".

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(One can think of the dot product between vectors as a special case of matrix products, but there are some subtleties required for that which it will not make you any wiser to care about at this stage).

unborn yacht
hushed sphinx
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So the short nice story is that a matrix can represent a linear transformation between two finite-dimensional vector spaces, each with a chosen basis (the side lengths of the matrix correspond to the dimensions of the vector spaces). If you take two linear transformations and chain them together, the matrix that represents the combined transformation is exactly the matrix product of the matrices that represent the transformation you started with.
However, the underlined terms are probably not familiar to you yet, and you'll need to learn those first before you can really appreciate why the matrix product is useful and why it has been defined the way it has. There's probably no royal road to that, other than grabbing a book (or similar source) on linear algebra and start from the beginning. The first few chapters should take you a fair way.
(And then the topic will belong better in #linear-algebra).

unborn yacht
smoky drift
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i need help with this please

hushed sphinx
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First simplify the definition of the function using a well-known trig identity.

smoky drift
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critical = d/dx

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when = 0

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i get these

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and idk how those cancel out to 0

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since if lets say 1 + -1 = 0

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but idk

hushed sphinx
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There's a sign error in your derivative.

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(But you shouldn't be using derivatives if the is only __pre__calculus, should you)?

smoky drift
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sry i was meting to want to put in ca;lc

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but didn't see tag chat

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so this is calc

smoky drift
hushed sphinx
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What is the derivative of cosine?

smoky drift
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-sin

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x

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-sin(x)

hushed sphinx
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Yes.

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So how did you get +cos(x)sin(x)?

smoky drift
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oh my god

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ok im just stupid, thanks for pointing that out

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ive been stuggling though this for hours

opaque bear
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hey idk if my brain is fried from doing hw all day but- is this not the right answer??? i thought the domain of all exponential functions was (-♾,♾️) ?!!??!

hushed sphinx
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Looks right to me.

opaque bear
calm fern
dark aurora
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you know what is vector ?

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you know what is oméomorhfils

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???

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phys

ebon barn
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If in a rational function, the curve crosses a horizontal asymptote, what would the end behavior be, would it still approach the asymptote?

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<@&286206848099549185>

tidal zenith
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@opaque bear it's (0,inf)

hybrid pewter
# calm fern

use the fact that the integrand is of the form (f(x) + f'(x))e^x for some choice of f(x)
you can derive a formula for the integral of (f(x) + f'(x))e^x by considering the derivative of f(x)e^x

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dont really know any way to motivate the solution though

calm fern
sand dune
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the two functions $f(x) = \frac{1}{x}$ and $g(x) = \frac{1}{x^2}$ show what happens really well

obsidian monolithBOT
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findingsouth

steep mason
icy yarrow
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Anyone her who just finished the math 30-1 diploma?

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Hereeee

marsh solstice
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Karaly, please don't ask that in every single group

icy yarrow
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@marsh solstice sorry just curious

zealous vigil
obsidian hinge
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also you probably shouldn't just give out answers :/

zealous vigil
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what should i attach more?

obsidian hinge
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hints

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although that is a beautiful solution wow

obsidian hinge
# obsidian hinge hints

something like "maybe you could try to rewrite this in terms of some sort of substitution?"

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and then the sqrt is the natural choice and it's obvious from there

zealous vigil
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okay I will take care of it

smoky drift
viscid thistle
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Is it possible to repeat a function a fractional number of times? For example f(f(x)) is 2 times

vapid plaza
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The short answer is no

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Probably because you’d need a new definition of “applying f to x n times” that extends the domain of n to other real numbers…
Which is, although possibly consistent with what your f is, often uninteresting🗿

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For example if f(x)=x+1 then I can define applying f n times as x+n which is consistent with our original definition…because applying f^1/2 twice will give the same result as applying f once
But for more complicated functions like f(x)= cos x, I doubt such a generalisation exists

willow bear
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the notion of "functional square root" is a thing but it doesnt exist for all functions

viscid thistle
void thorn
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well supposing you can, W^-1(x)=xe^x so I would maybe try the easier task of generalizing f(x)=xe^x by looking at f(f(x)), f(f(f(x))), ... to see if there might be a way through that first, then if you find something you can plug a number in, make it negative

dawn depot
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Anyone got any thinking questions for combining functions grade 12 advanced. Not too hard but can possibly be a test question. I want to practice

solar pagoda
obsidian monolithBOT
dawn depot
hushed sphinx
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Yes (if "infinite solusions" means "infinitely many solutions"). It's asking how to distinguish those (a,b,c,d) that do have the property from those that don't.

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Note that "all real x" means that some would-be solutions need to be discarded because because there's a single x that leads to division by zero even though f(f(x))=x for all other x.

viscid thistle
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If −7<x≤6
determine a and b for the inequality :
a<3x+8≤b

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Can anyone help me out with this?

hushed sphinx
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Try sketching a graph of 3x+8 in the interval from -7 to 6.

little parcel
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contour integral, how?

obsidian hinge
viscid thistle
obsidian hinge
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nw

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wait

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no i wasnt talking to u

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ur fine

obsidian hinge
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is who i was talking to

little parcel
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wrong channel

viscid thistle
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What do i do here

sage maple
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anyone good at polynomial division and can hop in a call for a couple minutes?

willow bear
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@viscid thistle do you still need help with this?

willow bear
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huge delay but ok

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okay so do you know how to evaluate one function at a point when you're given the function in this format (i.e. as a set of input-output pairs)?

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like, if i asked you to evaluate f(-2) for example, would you be able to do it?

willow bear
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right

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and do you know what it means when we add, subtract, multiply or divide two functions?

viscid thistle
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Yes

willow bear
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ok then what exactly is the issue here?

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you seem to know everything you need to know for all of these exercises.

viscid thistle
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I do not know what it wants me to do here

willow bear
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it wants you to calculate the given expressions or conclude their value is undefined

viscid thistle
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How

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It is a point

willow bear
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for example, (f+g)(-3) = f(-3) + g(-3).
you told me you were familiar with this. is that actually the case?

viscid thistle
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Yes

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then jhow would you do a point like(9,8)

willow bear
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oh, my bad, you took "point" to mean "point on the xy plane"...

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that's not what i meant

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sorry, it's common in higher math to refer to numbers on the number line as "points" when it is convenient

willow bear
viscid thistle
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Yes of course

willow bear
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ok

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then proceed similarly for all the other exercises in the section.

viscid thistle
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So how would I evaluate the point in the function

willow bear
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??

viscid thistle
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Can yo ushow me an example

willow bear
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am i understanding correctly that you are asking "How do I evaluate f(-3) and g(-3)?"

viscid thistle
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No

willow bear
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then what are you asking

viscid thistle
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How do you evaluate a two numbers in a fybnction

willow bear
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...i don't understand your question.

viscid thistle
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Can you show me an example

willow bear
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ok sure here's exercise 51:

(f+g)(-3) = f(-3) + g(-3) = 4 + (-2) = 2.

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is this what you were looking for?

viscid thistle
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Ok let see

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OH

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YOu find the x value in the set and output the y value

willow bear
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i mean... yes

viscid thistle
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Then you add it

willow bear
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that's how you evaluate a function that's given like this

viscid thistle
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I did not know how to do something given like this

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But now I do thank you

viscid thistle
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How do I solve this question: suppose you have a square with side lengths a and b which is inscribed in a circle with a radius of 10 cm whats the highest area the square can have

obsidian hinge
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figure out the largest square you can inscribe in the circle and find the area of it

willow bear
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did you mean a rectangle

uncut shoal
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"How do i solve this question" "200" jesse

frank vine
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Meant max area of square would be 200 un squared

sterile steppe
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can anyone help me with this? I keep getting 2 * cuberoot(4), and it gets marked as wrong

hushed sphinx
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I get that too.

sterile steppe
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Oh ok it must be a mistake in the test

last folio
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I need help with this question.

willow bear
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??

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what even is this

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"Find the equation of a hyperbola given this equation of a hyperbola"

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theres nothing to find???

last folio
last folio
willow bear
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ok

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@last folio do you still need help with this? sorry i only saw this now - was busy irl

last folio
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yh

willow bear
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are you familiar with the law of sines?

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it's going to be of use here

last folio
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yh

willow bear
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ok then are you able to apply the law of sines here?

last folio
willow bear
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bad handwriting + bad shape for root symbol + silent introduction of the variable x

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does x stand for angle B or angle C?

last folio
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angle B

willow bear
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ok then write B and not this strange "x" that came out of nowhere

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but yes you are correct angle B is indeed 30°

last folio
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okay

willow bear
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are you able to continue?

last folio
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no

willow bear
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you know two of the angles in your triangle.

last folio
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yh

willow bear
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is there anything else that you can calculate from this?

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ok, so what can you calculate from this?

last folio
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angle C

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45 + 30 + C = 180

willow bear
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great then do so

last folio
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Angle C = 105 degrees

willow bear
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are you able to finish this exercise now?

last folio
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yh buh I have with zero idea about it?

willow bear
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are we going to abandon the previous problem now?

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after we've walked through like 90% of it already?

last folio
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no

last folio
willow bear
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of course? there's still that third side that you haven't found.

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and instead you choose to throw another, unrelated problem at me.

last folio
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sorry bout that.

willow bear
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yes, AB.

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you have not yet calculated AB.

last folio
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yh

willow bear
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do it

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calculate AB

last folio
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how do I calculate for it.

willow bear
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you've used the law of sines once

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you are definitely able to use it again

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unless you refuse to do so on principle

last folio
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okay

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line AB = 13.52

willow bear
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sounds about right.

last folio
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Alright.

last folio
steel tulip
# last folio

If $x = t^2$ then $t = \sqrt{x}$ Then you substitute that value for t into the equation involving y and t to get an equation with only y and x

obsidian monolithBOT
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Tiessie

opal tree
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Then plug that t equation into the y parameter

bitter frigate
#

If you have to use a graphing tool they give you to graph a function, and that tool only lets you graph integers, do you just have to start plugging in random numbers and hope they end up being integers?
For example let's say you have to graph f(x) = 2(x-6)^2+2, and the graphing tool they give you only goes up to 20 on each axis, do I just have to plug in each number between 1 and 5 until I find an integer <20?

hushed sphinx
#

Who are "they"? Do you not have a pencil?

bitter frigate
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which would say something like "Graph this function" and you'd have to use the tool they give you on their website to submit your answer

celest yacht
bitter frigate
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right and since 6 is the axis of symmetry I'd only have to worry about one side right

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and then I plugged in 0 and got 74

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which gave me the 1-5 for numbers to check to be <20

celest yacht
bitter frigate
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oh I am dumb

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my mistake

royal ridge
obsidian monolithBOT
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Hallows

vital ivy
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@last folio it will be (y+2)**2 = x

warped knot
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oh

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can someone help me with

frank vine
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Here’s your answers

frank vine
willow bear
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@frank vine don't give out answers.

frank vine
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Alright but i included steps

snow bronze
# warped knot

You might wanna 'try' finding integral roots, for the leading coefficient is 1, check the integral factors of -192.

warped knot
#

Can someone@pls help w this

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Is due vv soon

bitter frigate
#

when applying transformations to quadratic functions why does addition shift x coordinates to the left, but when applied to y coordinates they get shifted up?

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specifically why do x coordinates get shifted left and not right

sly ocean
# warped knot

the unknown zero would be 3 - 3i since the polynomial has only real coefficients and according to the complex conjugate theorem: if a polynomial with real coefficients has a complex zero, the conjugate of the complex zero will also be a zero of the polynomial. after all, if a polynomial has real coefficients and complex zero, we need the conjugate of the zero to cancel out the terms with imaginary coefficients.

so the final answer would be (x + 5)²(x + 3 + 3i)(x + 3 - 3i)

sly ocean
# bitter frigate when applying transformations to quadratic functions why does addition shift x c...

if the input is added by 1 (turning x² to (x + 1)²), the graph shifts to the left since the inputs will be added by 1 before being evaluated

so if you input 1 you will get (1 + 1)² = (2)² = 4. the one becomes a 2 before being evaluated.

if you input 2 you will get (2 + 1)² = (3)² = 9. the 2 becomes a 3 before being evaluated.

basically the inputs are being "pushed" further by one

this applies to all functions and not just quadratic functions, i.e. all functions shift to the left if you add to the input before evaluating

#

feel free to point out any mistakes

bitter frigate
viscid thistle
sly ocean
# viscid thistle is there any proof of that theorem

In mathematics, the complex conjugate root theorem states that if P is a polynomial in one variable with real coefficients, and a + bi is a root of P with a and b real numbers, then its complex conjugate a − bi is also a root of P.It follows from this (and the fundamental theorem of algebra) that, if the degree of a real polynomial is odd, it mu...

viscid thistle
#

kk thx

sly ocean
#

here's a "proof" that is more easier to understand:

viscid thistle
bitter frigate
#

Are there any good videos explaining how this step works

willow bear
#

5-11 = -6

bitter frigate
#

oh lol

placid cairn
#

lmao

thorn valley
#

Can anyone help me understand this? I know how to do this process in reverse

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But this is more intimidating and complex it seems

willow bear
#

do you know how many minutes make a degree? @thorn valley

thorn valley
willow bear
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ok then let's forget about angle

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do you know how many minutes of time there are in an hour

thorn valley
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60

willow bear
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right

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the relationship between hours, minutes of time and seconds of time is the exact same as between degrees, minutes of arc and seconds of arc.

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1 degree = 60 arc-minutes and 1 arc-minute = 60 arc-seconds

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this should give you enough info to convert 0.7° into arc-minutes.

thorn valley
#

That would just be 0.7 * 60 correct?

willow bear
#

yes

thorn valley
#

Okay I understand you this far

#

So what would I do for seconds? Nothing...?

#

yay!

#

I got it!

#

Thank you Ann!

willow bear
#

not nothing

#

zero

viscid thistle
#

hey can someone help with a question?

#

i got -2x-y^2 cos(xy^2)/ 2xy cos (xy^2)

#

but im not sure if its correct

uncut mulch
#

do you have a pic of your work

#

its hard to read your result as it doesn't feel like you have parentheses where appropriate

prime moat
#

https://www.khanacademy.org/math/precalculus would this be enough before ap calc?

Khan Academy

The Precalculus course covers complex numbers; composite functions; trigonometric functions; vectors; matrices; conic sections; and probability and combinatorics. It also has two optional units on series and limits and continuity. Khan Academy's Precalculus course is built to deliver a comprehensive, illuminating, engaging, and Common Core align...

prime moat
# frank vine Probably yeah

so Im trying to learn precalc since I am trying to take ap calc ab after this summer. I dont thnk i can finish this khan academy actually within a month. Do you have any good idea I can use to learn all precalc stuff I need?

viscid thistle
#

For calculus I would want to know a lot of trig, exponential properties, logarithmic properties, systems of equations, and basic algebra rules

jovial cosmos
#

I’d just review parametric equations, conics, and polar coordinates (but I think some of this is bc, don’t remember)

#

That’s all you really need to know from pre-calc assuming you are strong in algebra (which you should definitely brush up in). Definitely some trig as in double angle formulas, thinking in terms of rad, sum and difference of angle formulas, but I learned that in alg 2 but I know some learn that in pre-calc

alpine wraith
viscid thistle
#

yea u kinda got confused

#

on where to put it

#

sorry

alpine wraith
#

no it’s fine I was just wondering

#

do you want help?

viscid thistle
#

no i got the answer the people in calc helped my thanks tho

jaunty pendant
#

starting calculus in grade 10 for gcses should i go to precalc or calc?

rare fiber
#

have you done pre calc before?

jaunty pendant
#

the chapter im doing in differentiation 1 and 2 but if i look it up calc comes is as one of the top results

hushed sphinx
#

If you're differentiating functions, then that is surely #calculus.

wooden field
#

Anyone know what this is?

#

wouldn't it be 2(-x)^1/2

solar pagoda
wooden field
#

so -2(x)^1/2?

solar pagoda
wooden field
#

Thank you

wild cypress
#

what sites would you recommend for precalculus??

#

Is khan academy good?

frank vine
#

Yeah

viscid thistle
#

what is a function which has derivative of all orders?

hushed sphinx
#

Looking for a definition, or for examples, or for the word "smooth"?

twilit jasper
placid cairn
#

e^x

solar pagoda
#

That is a polynomial 😀

willow bear
#

e^x is not a polynomial

solar pagoda
#

I have to start using these emojis stuff properly.

frank vine
elfin zinc
#

Can someone please explain me the reason of the intersection points of a function with its inverse its found simply equalating it to X. Example, f(x)=ax²+bx+C intersection points with its inverse can be discovered equalating ax²+bx+c=x and solving it. I am seeking to know a possible mathematical explanation for that.

uncut mulch
#

functions and its inverse are symmetrical across y=x

hushed sphinx
#

That doesn't find all intersections between (the graph of) a function and its inverse, though.

#

For example, f(x) = (pi/4 - 1)x - arctan(x) is bijective R->R, and intersects its inverse at (-1,1) and (0,0) and (1,-1); only one of these intersections satisfy f(x)=x.

#

The intersections with the inverse all correspond to solutions of f(f(x))=x, though.

elfin zinc
#

Yeah but what is the logic behind equalating the function to its varible to find inverse points?

elfin zinc
hushed sphinx
#

If (x,y) is a point on both the graph of f and the graph of f^-1, then one of those means y=f(x) and the other means x=f(y). Insert the former in the latter, and you get x=f(y)=f(f(x)).

#

This is in particular true if x=f(x), so solving that equation gives you some of the points of intersection.

viscid thistle
#

can someone give me insight on how this is wrong?

#

i thought it would be correct but i believe im missing something

vapid plaza
#

The denominator cannot be 0

viscid thistle
#

So will it be what I wrote + excluding - 8 and 8?

#

Wait not 8

#

Oh

#

-25 and 25 then

#

Okay that makes sense

fresh saffron
burnt lodge
#

Solve from there in the form of y=

ornate cargo
#

Hey whats up, i have a question, whats the differences between ⊆ and ⊂?

civic sierra
hybrid pewter
#

in some places ⊂ is used for subset and ⊊ for proper subset so just keep an eye out for context

#

i like to use ⊆ and ⊊ to avoid ambiguity

ember aspen
#

I dont understand this quesion

prime moat
#

would it be good idea to learn and review through the calculus readyness test? I just finished algebra 2 and now thinking of skipping precalc and go into ap calc ab

alpine wraith
#

@prime moat I’d recommend you ensure your knowledge of trigonometric, logarithmic, exponential, and rational functions first

#

And ensure memorization of the unit circle

#

most of the other stuff in precalc doesn’t pertain to calc

prime moat
#

i already know full unit circle yay

worthy coral
#

what does this notation mean $f(x)=min{x,x^2}$

#

<@&286206848099549185>

worthy coral
unborn cloak
#

Yea I do

worthy coral
#

pls tell

covert zealot
#

It is the minimum between the two elements

unborn cloak
#

It's the the minimum of the function x or x² so suppose at x=1/2 x²<x so we'll take x². Continue like this

worthy coral
#

and at 0<=x<=1 we will take x^2

#

thanks

unborn cloak
#

Yep

prime moat
#

ive went through ecponential laws, simplifying rationals, polynomial division

#

how far am i for ap calc preparation

digital lance
#

Hey guys sorry to bother you studying for my exam at the moment and these logarithms equations are brutalizing me. Would appreciate some help.

humble elbow
#

Pre caluclator

digital lance
#

hm?

humble elbow
#

I need help

viscid thistle
#

hey guys. I’m a new 9th grader and I need help learning calc, dm me.

wintry tide
#

Helllo

hybrid pier
#

does a reciprocal function need to have a numerator of 1?

hushed sphinx
#

What is a "reciprocal function"?

#

The reciprocal function is the one that maps x to 1/x for every x.

ripe palm
#

Hey, does anyone know how to do word problems like this?

#

<@&286206848099549185>

obsidian monolithBOT
#

Eren Yeager

summer basalt
#

need some hints

#

ping me while replying

ember aspen
#

how can you simplify the logarithm in the left hand of the equation?

daring drum
#

Ty

bitter frigate
#

So graphs can intersect with asymptotes? Or only horizontal asymptotes?

#

And can they fully cross an asymptote if they do intersect?

#

And if horizontal and slant asymptotes can be crossed, what are they actually there for?

pastel magnet
uncut mulch
#

As far as I'm aware, a graph can't intersect its own asymptotes, that's the entire point - the function approaches the asymptote, but never crosses it after a finite distance.
no

#

misconception

#

for example take y=sin(x)/x
that has a horizonal asymptote of y=0
but crosses the that infinitely many times

bitter frigate
#

Or is that not true?

uncut mulch
#

no

#

stuff like horizontal and slant asymtotes describe end behaviour

#

and by themselves don't say much about anything else

bitter frigate
#

oh interesting, I'm guessing their use will make more sense to me once I'm deeper into calc

ripe palm
#

The top photo contains the details, the bottom are the individual questions

#

The pencil stuff is from me, and might be incorrect

#

<@&286206848099549185>

thick berry
#

Does anyone know how to find the two imaginary roots

#

<@&286206848099549185>

summer basalt
fluid yacht
#

Please help me q 7 and 8 <@&286206848099549185>

hushed sphinx
bitter frigate
#

Why when somebody asks for the x intercept, you don't need to specify which axis your answer's on, but if somebody asks for the vertical asymptote, you need to specify with x= before the value?

#

Is the second example not implicit like the first example?

#

for example:

vapid plaza
#

The x-intercept is the “number” on the x-axis which the curve passes through
The asymptote is the “line” which the curve approaches

#

Therefore to represent that line you need to use an equation for that line, say x=7

bitter frigate
#

oh that makes sense, ty

bitter frigate
#

Is there a reason why this specifically says third row and not quotient? And is this true for normal polynomial division as well?

burnt lodge
bitter frigate
echo mortar
#

hey can someone help me with a question i have?

cobalt knot
echo mortar
#

for sure

#

i dont understand how i could rewrite it

#

and the textbook also doesnt really help me

#

could anyone help me with these couple of questions?

#

i want to be able to understand the concept better

uncut mulch
#

try not to overthink this

#

a = b + c
means
b = ?

echo mortar
#

?

#

a=b+c

#

b would be log4(x-3)

#

if i am understanding your explanation correctly

uncut mulch
#

yes

echo mortar
#

ye

#

so hhow can i rewrite log4(x-3)

#

im sorry but idk how a = b+c plays into this

uncut mulch
#

this is currently for the first box that you left blank

echo mortar
#

yea log4(x-3) was not the answer unfortunately :(

uncut mulch
#

I know

echo mortar
#

oh what

uncut mulch
#

try not to overthink this

#

a = b + c
means
b = ?

echo mortar
#

when yousaid yes i thought you meant that was the answer

#

well i got that one wrong, but ill try to learn it still

#

b= log4(x-3)

uncut mulch
#

the yes was to the b representing log_4(x-3) in the equation

echo mortar
#

i c

uncut mulch
#

but what I wanted was to forget about logs for a sec

#

and if you were just given
a = b + c

#

what would you answer if you were asked for
b

echo mortar
#

b

echo mortar
#

unless you mean like

uncut mulch
#

it was implied

#

clearly they don't want you to its say stuff like x = x

echo mortar
#

yea i know that much

#

i didnt know you want to forget about the log

#

so would b = 4?

uncut mulch
#

not

#

forget about everything else for a sec

#

given
a = b + c
b = ?

echo mortar
#

okay forget everything else for a se

#

if i am just given a = b+c on a piece of paper

#

and you ask what b is

#

i would say that b is b

uncut mulch
#

forget about everything (in the question)
don't forget about basic algebra

#

don't forget about a=b+c

#

clearly they don't want you to its say stuff like x = x
I don't want you to its say stuff like x = x

echo mortar
#

i understand that

#

idk what you mean by basic algebra when you say that

muted turret
#

Yo why is plotting points without a calculator so hard

echo mortar
#

use desmos and get the graphing calculator

muted turret
#

idk what to do for the next steps it is so hard smh

echo mortar
#

stuff is mad helpful

muted turret
#

Does the parabola opens downwards I am not sure

#

Cause ax is negative

echo mortar
#

oh you probably have ot factor -x^2+2x+3

#

factor that, and you get your 2 x intercepts

#

and then try to find the vertex wiht a formula (i forgot which one) and you can plot it that way

uncut mulch
#

perhaps I might have to make it extremely clear
starting with a=b+c
if you were asked to solve for b
(as implied by asking b = ?)
what would you do?

muted turret
#

I did

muted turret
echo mortar
uncut mulch
#

to get additional points, choose some values of x, plug into the equation to get the respective y values to get your points

muted turret
#

ohhhhh

uncut mulch
#

using nice integer values will make your work easier

#

you can also consider symmetry

echo mortar
uncut mulch
#

it was pretty clear I wanted you to isolate b I'm the equation I gave you

#

if I wanted you to respond with b=b
I wouldn't have even mentioned the equation a = b + c

echo mortar
#

okay sorry for being dumb ig and not being able to read it the way you read it

#

oh well it is what it is, ill just take the L

muted turret
#

My first parabola done without a calculator 💪💪💪

vapid plaza
#

Looks kinda not like a parabola ngl

#

But nice

sinful dome
#

Help pls

warped knot
fleet forge
#

Can I get some help please!

willow bear
#

@fleet forge do you still need help with this

zenith solar
#

Can someone help me with this please

willow bear
#

,rccw

obsidian monolithBOT
zenith solar
#

I’m not sure if this will help but here is my working out, I’m not sure what to do past here/if I did anything wrong

willow bear
#

your work is correct and you already have the answer

#

P(-1) = 5

heady horizon
fleet forge
willow bear
#

14 hour delay but ok...

#

do you know, in general, what an arithmetic sequence is

fleet forge
#

Sorryy

#

Yeah

willow bear
#

ok

#

can you describe in your own words what it means for a sequence to be an arithmetic sequence?

fleet forge
#

Basically a set of numbers that are in order and it’s made out of terms and is a list of numbers where the difference or distance between consecutive terms is a constant

willow bear
#

...well there is a kernel of truth in that, i'll give you that.

#

it's a sequence in which the difference between consecutive terms is always the same

#

and this difference is called, fittingly, the common difference.

fleet forge
#

Ohhh

willow bear
#

now, you have the sequence that begins -38, -47, -56, -65, ...

#

what is its common difference?

fleet forge
#

-9

willow bear
#

correct

#

now you know the first term (among others) and you know the common difference

#

do you understand now how to write down an expression for the general term?

fleet forge
#

Isn’t the general term tn= a + (n-1)d

#

So would it be tn= -38 + (n-1)-9

willow bear
#

careful there

#

(n-1)-9 looks like you are subtracting 9 from (n-1), which is not what the formula you quoted says

#

you need to multiply (n-1) by -9

#

so you would want -38 - 9(n-1)

fleet forge
#

Right

willow bear
#

or, if you want to be absolutely 100% adherent to how the formula is written, -38 + (n-1)(-9) or something

#

but that's kind of silly

fleet forge
#

Okie thank you

fleet forge
willow bear
#

if you wanna simplify it sure

#

that works

fleet forge
#

Thank you for the help!

alpine wraith
#

@willow bear out of curiosity what was the process of getting honorable?

willow bear
#

that is classified information.

zenith solar
#

How do you show that there is only one rational zero

willow bear
#

well you've found one

#

now you can factor it out and show that the quadratic that remains doesn't have any rational zeros

zenith solar
#

Thanks

zenith solar
#

Sorry for the multiple questions but I’m not sure how to approach this

willow bear
#

you can rewrite P(x) by completing the square

zenith solar
#

What do you do after that?

willow bear
#

show me what you got from rewriting the thing

#

then we'll talk

zenith solar
willow bear
#

who said c = 4?

zenith solar
#

Oh

#

Then I’m not sure how to factor a quartic 😅

willow bear
#

well you could modify what you have here to not be wrong

#

$x^4 - 4x^2 + c = x^4 - 4x^2 + 4 + (c-4) = (x^2 - 2)^2 + (c-4)$

obsidian monolithBOT
willow bear
#

the equation P(x)=0 thus rewrites as (x^2 - 2)^2 = 4-c

#

thus if 4 - c < 0 then there are no real solutions

#

and if 4 - c ≥ 0 then there is at least one

zenith solar
#

Ohh that makes sense, thank you 🙏

alpine creek
#

I need some explaining on these problems

worthy coral
willow bear
#

sully don't ping random ppl out of the blue like that

worn venture
#

How to solve this

viscid thistle
obsidian monolithBOT
viscid thistle
obsidian monolithBOT
viscid thistle
#

Solve it by removing the 1dx, so we can solve 1/x4 on its own: $\int\frac{1}{x^4}dx$

obsidian monolithBOT
viscid thistle
#

@worn venture

#

Now solve $\int1dx$ which would give you x

obsidian monolithBOT
viscid thistle
#

Now sub in the integrals: $x-\frac{1}{3x^3}$

obsidian monolithBOT
viscid thistle
#

Done! The answer is $x-\frac{1}{3x^3}+C$

obsidian monolithBOT
viscid thistle
#

I think

worn venture
#

Can you please write it on a paper

#

I didn't get the whole idea

#

If it is possible then please write it on paper

viscid thistle
#

I'm sorry, I don't have any to hand.

viscid thistle
modern valve
#

hello

modern valve
#

this isn't right

viscid thistle
#

Am I doing the wrong method?

modern valve
#

square root of (1 + 1/x^4) is not 1 + 1/x^4 ?

worn venture
viscid thistle
#

Sorry I'm still getting to grips with LaTeX

worn venture
modern valve
#

likely you are not supposed to evaluate the integral

viscid thistle
#

Sorry about this, I was being stupid

worn venture
modern valve
#

no I mean like the question text too

worn venture
#

I just need to know how to solve this integration that's it

modern valve
#

you can't by hand

#

so i'm trying to figure out what the context of it is

worn venture
modern valve
#

can you like post the full page maybe

worn venture
modern valve
#

:|

#

can you state like what the full problem is

#

I might be able to help better

obtuse jasper
#

$\sqrt{\frac{x^4 + 1}{x^4}}$

obsidian monolithBOT
#

MathOnNapkins

obtuse jasper
#

And maybe trig substitute / integrate by parts 🤔

worn venture
modern valve
modern valve
fallen pecan
#

i am trying trig

worn venture
modern valve
#

wolframalpha gives it in terms of a hypergeometric function

modern valve
#

besides just plugging it into the calculator

fallen pecan
opal tree
#

Why are integrals in the precalc section

burnt lodge
#

But they shouldn’t be there

viscid thistle
#

yes

next cipher
#

hey guys im gonna take precalc next school year and i was wondering what math i should brush up on to help me have an easier time
i feel like most of my mistakes are because i am not careful enough

mild swan
obtuse jasper
#

I honestly can't even remember what I specifically learned that I hadn't seen before in Precalc. Probably Trig. Otherwise it seemed like a lot of drilling preparation for Calculus

burnt lodge
#

Preparing for the preparation is Algebra and Geometry

twin quest
#

in terms of parametrics, when would I use the first y = formula and when would I use the second y = formula?

twin quest
#

nvm i figured the first one is in feet/sec and the other is meter/sec

willow bear
#

if you're trying to memorize both of these formulas then you're setting yourself up for overcomplication and failure

#

if anything the middle term should be $-\frac{1}{2}gt^2$, where $g$ is gravitational acceleration

obsidian monolithBOT
viscid thistle
#

am i missing something here?

#

i thought it would be right but apparently not

willow bear
#

when is sqrt(x^2 - 64) = 15?

viscid thistle
#

Oh i am such an idiot

#

i mistook -13 and 13 with -17 and 17

#

that makes sense

#

On another note, how could someone go about finding specific functions in composite functions?

#

To find f(x) in something such as f(g(x))

#

I always used intuition to find them but it doesn't seem very efficient, is there a more reasonable approach?

willow bear
#

if all you're given is f(g(x)) then there cannot be a "more reasonable approach"

#

because compositional factorizations like this are not uniquely defined

viscid thistle
#

For example "Find g(x) given f(g(x)) and f(x)"

#

Or for f(x)

willow bear
#

i mean in that case if f happens to be invertible then g is recoverable as f^-1 composed with f o g

viscid thistle
#

Oh!

#

I never thought about that

#

Canceling the functions by taking their inverse

#

Yeah that does seem very reasonable thank you

astral bobcat
#

sorry i have a question
lim x -> 0, sinx/x = ?
without consulting derivatives

willow bear
#

are you allowed to use the squeeze theorem

astral bobcat
#

yes but

#

is it work

willow bear
#

do you mean "does it work"?

astral bobcat
#

yeah sorry

willow bear
#

prove $\cos(x) \leq \frac{\sin(x)}{x} \leq 1$ for $x$ sufficiently close to zero. that'll get you a proof that $\lim_{x \to 0} \frac{\sin(x)}{x} = 1$.

obsidian monolithBOT
viscid thistle
willow bear
#

yes

viscid thistle
#

ah i see, seems complicated

viscid thistle
#

I would imagine using sandwich theorem you would have something along the lines of -1/x and 1/x on both ends

willow bear
viscid thistle
viscid thistle
astral bobcat
viscid thistle
#

ohh i thought we were talking about x as it approaches 0

#

yeah makes sense

willow bear
astral bobcat
#

i understand thank you

#

i can't proof cosx < sinx/x < 1

#

$\cos(x) \leq \frac{\sin(x)}{x} \leq 1$

obsidian monolithBOT
#

theman

astral bobcat
#

i mean this

willow bear
#

can you prove that sin(x) <= x for positive x?

#

and that tan(x) >= x?

#

i don't know if you have a formal definition of sin and cos on which you are supposed to base your proof.

#

@astral bobcat

astral bobcat
#

the mean value theorem?

willow bear
#

...

#

mean value theorem relies on derivatives so that is a no-go.

#

tell me what your class's definition of sin(x) is.

astral bobcat
#

the opposite side of the angle divided by the hyptenuse in a right triangle

#

well not exactly

willow bear
#

...

#

then show me the EXACT definition for god's sake

#

how the fuck do you expect to produce any sort of proof if you don't even have any definitions on which to base it???

astral bobcat
#

that's the deifinition i can express

#

i don't knoow

willow bear
#

no definition no proof

#

simple as that

#

maybe look through your notes or ask a classmate

astral bobcat
#

how about i get the unit circle

willow bear
#

ah well NOW we're talking.

astral bobcat
#

get a triangle with the field cosx.sinx/2

willow bear
#

with area cos(x)sin(x)/2.

astral bobcat
#

and a circle slice with pi.1^2.x/2pi

vapid plaza
#

You mean a sector?

astral bobcat
#

and a bigger triangle with the area tanx/2

#

and compare the areas

#

you know what i get it

placid cairn
#

circle slice

#

LMAO

wise spoke
#

can i ask about diffrentiation here?

vapid plaza
wise spoke
#

How many turning points would a function $y = \frac{f(x)}{g(x)}$ have if the power of both f(x) and g(x) is two and the discriminant of f(x) < 0?

obsidian monolithBOT
#

∫Inheritanc-e ♦

willow bear
#

do you mean the degree of f and of g are both 2

#

@wise spoke i believe that this info alone is insufficient to determine the number of turning points

#

there exist rational functions satisfying your requirements with 2, 1 and even with 0 turning points

copper vigil
#

,w d/dx (ax^2 + bx + c)/(dx^2 + ex + f)

#

that's a start i guess

obsidian monolithBOT
edgy spruce
#

Take it to calculus

alpine wraith
#

sigh

#

<@&268886789983436800>

stuck lark
#

already gotem

alpine wraith
#

gracias por te ayuda