#precalculus

1 messages · Page 44 of 1

stable knot
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sorry, again

proven night
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By the way

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2^x - 3^x = - 1

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So can we say that lhs is monotonously decreasing function?

hallow tide
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no

proven night
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Why did you delete it?

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how do i determine whether a function is monotonous?

hallow tide
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with calculus

proven night
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So cant i solve precalculus exponential equations without it?

proven night
summer ruin
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if you can show that x < y implies 2^x - 3^x < 2^y - 3^y or that x > y implies 2^x - 3^x > 2^y - 3^y, then you will prove that the function is monotone

slender hedge
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f:g:h g is 60 percent more than h , f is a third of g , simplify f:g:h

thorny prism
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Hello! Idk where I can ask it tbh, because it is a simple thing. Is there a general formula for derivative of f(x)=u(x)•v(x)•w(x)•…? I mean I can find the derivative of the ‘triple’ product, it isn’t that hard but is there a general way? Because if I would have to find the derivative of the of 6 functions, I will spend a lot of time counting a lot of default derivatives for the product of two functions

paper tartan
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I made a mistake, the first link shows you show to differentiate a product of two functions n times

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the second link gives you the derivative for 3, and then k functions

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just below that, you can also find out how to differentiate a product of k functions n times

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there's also stuff for partial derivatives, but I'll let you explore all of that lol

thorny prism
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Thank you so much!

I haven’t got calculus because, I think, I have only got pre-university group… my bad with it

paper tartan
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type ,iam advanced in #bots

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that should let you type in #calculus, and the other early uni/adv math channels too

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oh, you've taken the UG role

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that works too!

thorny prism
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Thank you!

paper tartan
viscid thistle
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I just got the AoPS Precalc book and I'm stuck on trig unit circles :-: does anyone know the basics to it?

chrome ether
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that's not nearly a specific enough question

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try again

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what don't you get about it?

viscid thistle
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Hold on lemme find a picture

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ok so for example you have graph sinx=sin(x+2π)

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and it asks if it's periodic and if so find the period

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how am I going to solve this question?

bronze rock
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Having trouble understanding why multiplying the x value in a trig function, decreases the length of a period.
It just doesnt make logical sense to me. I feel like it would make more sense, for it to be reversed instead of 2pi/b.
Why not just 2pi * b, since you would be multiplying the input x value?

hallow tide
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trig functions aren't special

viscid thistle
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@bronze rock Thanks for the explanation! I think I got mixed up lol

hallow tide
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f(ax) represents a horizontal dilation of f(x)

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when |a| > 1, the function is compressed; when |a| < 1, the function is stretched

bronze rock
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Yeah I just find it super odd that its a dilation I guess. It just seems reversed logically to me

muted shore
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wat is

bronze rock
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multiplying the x value of a function.
Its Inverse Variation which I find weird

hushed sphinx
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Suppose f(x) is periodic with some period and consider g(x)=f(2x).
Then you only need half of the x before g starts repeating.

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Since multiplying by 2 means you can reach a certain input for f without spending as much x as you would need to if you fed x directly into f.

bronze rock
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Ah I see. That makes sense. Thanks

muted shore
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oh ur talking about why 1/a is a stretch but multiplying by a is a compression

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im guessing

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ya does seem p reversed

tired stone
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how do I get the instantaneous rate of change

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?

willow skiff
umbral crow
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i need a bit of help with precal

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the question is "graph f and g on the same set of coordinate axes (include two full periods)"

willow skiff
tender questBOT
willow skiff
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oh ok

umbral crow
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f(x) = -2 sin x

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g(x) = 4 sin x

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i kind of forgot like everything so im struggling with how to graph individual ones

willow skiff
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like what's sin 0 for example

umbral crow
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i have the graph memorized

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but like im still kinda new on the entire concepts of graphs and stuff

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sin 0 = 0?

willow skiff
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oh right, that's good then

willow skiff
willow skiff
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what the -2 and the 4 do when multiplied by sin x is that they stretch the y-direction

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so 4 sin x stretches the y-direction by a factor of 4

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in other words the max is now 4 and the min is now -4

umbral crow
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ohhhh

willow skiff
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-2 sin x is similar but after you stretch the graph by a factor of 2, you reflect it across the x-axis (flip it upside down)

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you flip it upside down when there's a minus sign multiplied by sin x

umbral crow
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wait so it's like normal rules of transformations

willow skiff
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exactly

umbral crow
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okay wait that made so much sense

willow skiff
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cool sounds like something didn't click for you and that you actually know your stuff

umbral crow
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thank you for the help 🙏

hearty granite
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looking for some hlep in studying for cal final if anyone is interested

shadow summit
flat shuttle
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What does it want me to say when it asks for an explanation for my reasoning

chrome ether
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why do you conclude the answer that you do?

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(if it’s a polynomial, just state the parity of the degree (even/odd) and the sign of its leading coefficient (positive/negative))

flat shuttle
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ok

gritty ibex
autumn snow
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Hey could someone help me with this one question

daring tapir
tender questBOT
paper tartan
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right, you can't see that channel, can you?

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that's good enough

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the role is meant for people who study undergradate math

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you don't necessarily have to be an UG for it

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many are not

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#calculus is the channel for calculus discussion

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this one is suited for precalc

ashen flame
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I need to solve for the critical values of cos(2x)+sinx+1=f(x). I set the derivative equal to zero and got 0.25 and 2.9. However, there are two other critical values that I don't understand how to get mathematically.

summer ruin
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there are infinitely many critical points, not just two or four

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you need to show your work

low slate
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How far does pre-calculus go? When does it end? Like- i took the 5 rules of derivation and some integration techniques, am i at calculus 1 or pre- calculus

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The last two lessons i was taught: how to differentiate trig functions and applications on derivatives

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Next year first two lessons:how to differntiate functions in parametric form and implicit differentiation

paper tartan
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take the Undergraduate Math role in id:customize, and then go to #calculus if you have calculus-related problems

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this channel is for the usual precalculus curriculum

low slate
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Higher is like

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The infinte version of high

paper tartan
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higher! lisayay

low slate
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You cant get higher than higher

paper tartan
low slate
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So higher is infinity

low slate
paper tartan
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now you have it

low slate
tired stone
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did I do it correctly?

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<@&286206848099549185>

dire aspen
tired stone
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bro

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pls help me

paper tartan
paper tartan
proven night
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If two men are moving towards each other, the first one with speed 10 m/s and the second one with speed 7 m/s, how soon will they meet

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And the distance between them is 100 m

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I dont understand how to solve this kind of porblems

stoic rivet
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100/(10+7)

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If they move towards each other u add the speed
If they leave each other then subtract two speed

proven night
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it makes sense

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I did almost the same: 10t + 7t = 100

proven night
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Hello

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I think i should replace 4x (i dont have theta character in my keyboard) with t, so the equation is gonna look like this: cos t + cos 2t + cos 3t = - 1

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Is there an easier way of solving this equation without cos 3t identity?

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I mean i always confuse cos 3t identity with sin 3t identity and it's hard to remember it to me, so maybe one can solve the equation without it?

sturdy token
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@proven night

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i used 3 identities, cos x + cos y
cosx - cosy and sin2x

proven night
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Thanks, but the equation has more solitions as far as i remember

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I solved using cos 3t identity

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However thanks, i should learn sum of cosines identity

sturdy token
# proven night

yea it would have more, but keep in mind that theta is between 0 and pi/2

tired stone
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do the numbers look correct?

willow skiff
obsidian monolithBOT
willow skiff
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,w log_3 (36)

obsidian monolithBOT
willow skiff
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I don't get how you came up with those values

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you just draw horizontal lines y = 17 and y = 36 on your graph

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cause $3^{\log_3 17} = 17$ and so on

obsidian monolithBOT
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southy

tired stone
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oh

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ok

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that makes more sense

willow skiff
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no worries

tired stone
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log 3 (17)is 1.707 though

willow skiff
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and you shouldn't get that value from your graph

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should definitely be 2 point something

tired stone
willow skiff
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try typing _ after your log

tired stone
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ohhhhhhhhhhhh

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that makes more sense

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thank you again

willow skiff
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no worries again

tired stone
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so it gives me 2.5 but how do I graph it?

willow skiff
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and then you can type in y = 17, y = 36 on different lines

tired stone
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how did you get 17 and 36?

willow skiff
tired stone
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ohhhhhhhh

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ok

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thank you again

tired stone
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How does that look?

ashen flame
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how do i prove that the derivative of sin x is cos x

chrome ether
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at least take a few seconds to google it first

eager narwhal
hollow jungle
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and the sin addition formula, $sin(x + h) = sin(x)cos(h) + cos(x)sin(h)$

obsidian monolithBOT
proven night
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I see several identities at the same time, but it didnt help me at all

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I just dont even know what should i start with

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I tried expanding sin 4x and sin 2x but it was still useless

daring tapir
daring tapir
# proven night

Wait are you trying to prove this or find solutions?
Cuz if prove then its not possible as the statement is wrong (look at x=0)

proven night
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It's an equation

proven night
daring tapir
proven night
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i got 2sin(x)cos(3x) = 4cos^2(x) -3

daring tapir
proven night
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As sum of 2x and x or as a cosine of triple angle?

daring tapir
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Latter

proven night
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Okay

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i got 8sin(x)cos^3(x) - 6sin(x)cos(x) - 4cos^2(x) + 3 = 0

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But i dont know what how exactly should i factor this

daring tapir
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Take 2sin(x) cos(x) common

proven night
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Ok

daring tapir
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(Please ping when responding)

proven night
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Alright

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@daring tapir

daring tapir
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Hm

proven night
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Thanks, @daring tapir

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I factored it

proven night
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Because i hardly ever use them, however this equation used both

daring tapir
proven night
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I dont know how to derive it

daring tapir
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Look it up its easy enough

proven night
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Okay

near basin
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I have forgotten limits
Why is the limit as x approaches 0 36?

\frac{\left(\sin\left(6x\right)\right)^{2}}{x^{2}}

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My first thought is infinity since {x^{2}} is in the denominator

summer ruin
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$\lim_{x \to 0} \frac{\sin (x)}{x} = 1$

obsidian monolithBOT
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Transparent Elemental

near basin
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How is that proved?

summer ruin
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you can google the proof

near basin
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I mean the equation you gave me

viscid thistle
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guy just tell me one thing

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does product rule for integration exist or nah

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cuz my physics teacher told me there aint nothing like tha

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but a book i follow has a rule formula named "integration by parts"

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and google says i exists too

summer ruin
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product rule would say something about the integral of a product of two functions

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which you can't say anything about

summer ruin
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that's what product rule for derivatives does

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it relates derivative of a product to derivatives of something simpler

viscid thistle
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oh

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i somewhat get it somewhat dont ( im new to calculus thats why lol)

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so like u get the answer but it isnt exactly what you would get

abstract gazelle
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How to do this?

round current
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could someone explain thsi for me

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i dont get what i got wrong

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its coming to zero from the right side

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and i dont get how it works cuz there are holes

winter comet
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The limit looks at behavior near the point rather than the point itself

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The graph is approaching 0 from both sides as x -> 0

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As far as the graph, there is a hole at (0,0) they didn't draw well or at least it's hard for me to see

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But otherwise it wouldn't be a function

round current
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ohhhhhh

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thanks

viscid thistle
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How can I apply taylor series to a limit?

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For example, I wanna solve this limit when x tends to 0 of sin (x) divided by x using Taylor series.

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$\lim_{x \to 0} \frac{\sin (x)}{x} = 1$

obsidian monolithBOT
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Machholz

fading monolith
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But you just need to substitute the sin(x) with its power series at 0 and then divide it by x. Since the series converges uniformly then you can interchange limit with infinite sum and thats it

agile sparrow
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f(x) =x+3

narrow briar
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Hi!

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Do you know any nice web where I can find integral excercices by substitution?

vapid frigate
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Could some explain the difference between chain rule and product rule?

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I'm kinda stuck lol

viscid thistle
vapid frigate
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Oh thanks

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Sorry btw

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It wasn't in my channel list

viscid thistle
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Hey, so I wanted to learn calculus and downloaded the book Calculus: Early Transcendentals by James Stewart, and realized that I have huge gaps in the knowledge required from the diagnostic test.

I am currently 12 months in my 14 month army service in Cyprus, and things are starting to get easier. Every 6 hours, I have a 3 hour number where I basically just sit on a desk and write the credentials of anyone that takes out our puts in a gun. That is a great time to study, and I am currently just wasting that time on my phone.

Can you recommend a good precalculus book that will cover everything extensively? If I can't finish it during the next two months, I am prepared to put in the work in University as well.

Thanks!

lime nymph
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Hello. This is 9th grade math (functions). I don't know how to do the exercise in the middle. It's in spanish so I'll try to translate it:
"According to the following conditions for the functions k(x) and t(x)
k(2)=4, k(4)=8, k(6)=2, k(8)=6
t(2)=4, t(4)=8, t(6)=8, t(8)=4
Determine.
a. (kot)(2)=
b. (tok)(2)=
c. (kot)(6)=
d. (kot)(4)=
e. (tok)(8)=
f. (tok)(6)="
Please help.

outer oxide
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B:
(t o k)(2) = t(2) o k(2) = 4 o 4

lime nymph
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"o" is the function composition

outer oxide
lime nymph
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I tried doing that, but every result ends up being 8 except 2.
I tried k(t(2)) = k(4)=8.
I also tried k(8)= 8(8)=64
or 2(2)(2)=4(2)=8

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(f o g) is (k o t), I know that much

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but the (2) instead of (x) messes me up

outer oxide
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well it has to be that way, the 8s might be only coincidence

lime nymph
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;( maybe

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anyway thank you

outer oxide
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no problem

viscid thistle
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Pre calc humbles me

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(Never done pre calc)

winter comet
viscid thistle
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Idk js never done it

winter comet
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what do u know about it

viscid thistle
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Nun

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Which is why it humbles me

paper tartan
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everything is hard when you've never done it before

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especially in mathematics

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don't be too discouraged!

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practice makes perfect, as they say thumbsupanimegirl

elfin cargo
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What do you guys learn in pre-calc?

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I don't think my country has pre-calc breadthink

willow skiff
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I'm not American and only American people call it precalc

elfin cargo
willow skiff
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factor and remainder theorems, polynomial long division

tender mist
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Depending on your depiction of "america". It's not just the US, Canada has it too

willow skiff
willow skiff
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but Ontario calls it advanced functions

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BC calls it precalculus I think

tender mist
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MB calls it precalculus, yep

willow skiff
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ahhhh right yeah just not Ontario fair enough

willow skiff
tender mist
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Who knows opencry Even calculus courses go by different names in different places

willow skiff
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exactly

lapis sphinx
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We did so much in precalc

elfin cargo
tender mist
#

Anyway, yeah. Precalc by the cirriculum I had was teaching exponentials, logarithms, trig, rational functions, and inverse functions

tender mist
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It's because calc courses go by different names, but never mind, that has nothing to do with actual alternative math names

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I often say calc 1/2/3, just because generally speaking, even if places do things a bit differently, most people are able to distinguish between what content goes inside of those

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I guess saying differential calc, integral calc, and multivariable calc is even better though

willow skiff
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there's not just single-variable calculus but also multivariable

tender mist
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Not like I really know much about calc yet. I only recently finished calc 1, and have just brushed the surface of calc 2, lol

elfin cargo
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I also often call calc 1, 2, 3 but my university have different courses on them

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But calc 1, 2, 3 look universal enough so everyone know what in it

tender mist
#

Calc 2 is the only one at my university that goes by that name

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Calc 1 goes by "Introduction to Calculus", which is honestly a pretty fair name. And calc 3 goes by "Multivariable Calculus".

proven night
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Hi

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Can anyone help me with it

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I tried applying difference of cubes formula and i also tried solving the system of equations but neither helped me

raw hill
obsidian monolithBOT
#

Civil Service Pigeon

proven night
#

I did it

winter comet
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thats the difference of cbes formula lol

proven night
#

And replace a-b with 9

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And divided 27 by it

winter comet
#

you can replace a with b + 9 then

raw hill
#

^

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you can do that or reduce it to a system in (a+b) and ab

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Using the fact that:

  • ||a^2 + b^2 = (a+b)^2 - 2ab||
  • ||(a-b)^2 = (a+b)^2 - 4ab||
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(Note that a and b are complex numbers that aren't particularly nice to work with)

raw hill
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especially b/c they explicitly ask for a product

proven night
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What do you mean by reduce it to a system in a + b

raw hill
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I should've said "rewrite a^3 - b^3 in terms of a+b and ab" tbh

proven night
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But i dont have a^3 + b^3. Instead i have a^3 - b^3

raw hill
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Typo, the idea still holds.

winter comet
#

you should have 9(a^2+ab+b^2) = 27

raw hill
#

? they said "27 by it" not "it by 27"

winter comet
#

you can divide by 9

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oh

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um

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don't do either?

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oh

raw hill
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And replace a-b with 9
And divided 27 by it

winter comet
#

wait do you mean divide 9 by 27>

raw hill
#

it's clear "it" refers to 9

winter comet
#

oh ok

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yea then just replace a with b + 9 yeh

raw hill
raw hill
raw hill
winter comet
#

oh yeh tru

warped shuttle
warped shuttle
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Here is the formula i used

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i think it's easier than doing a system

viscid thistle
left crystal
#

idts

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it's a variable r. which is = ab that we have to find

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a-b = 9

warped shuttle
#

a simple variable

livid hinge
#

bird $$3+3*3$$

obsidian monolithBOT
livid hinge
#

wow nice formatting

jagged vine
#

these r just homework questions I cannot figureo ut

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would love some help

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also how is this the wrong slope?

winter comet
jagged vine
#

i just dont understand them

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the sqrt root really throw me off

winter comet
#

you can rewrite the square root(f(x)) as [f(x)]^(1/2)

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and then you can use the chain rule

winter comet
#

how to differentiate it?

jagged vine
#

yes

winter comet
#

you know how sqrt(x) = x^(1/2) ?

jagged vine
#

yes

winter comet
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so like sqrt(x+2y) = (x+2y)^(1/2)

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right

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and sqrt(3xy) = (3xy)^1/2

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and then you can use chain rule right?

jagged vine
#

yeah i wasnt thinking ab it like that

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ty ill try it

cerulean canopy
#

i need help am i cooked

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-4 > |x| > 4

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is that right??

viscid thistle
#

And no it’s not correct

viscid thistle
chrome ether
#

absolute values cannot be negative

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what you have there is satisfied by the entire real line

viscid thistle
cerulean canopy
#

thanks

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i got it

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figured out \

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👍 '

white rapids
#

Could somebody clear this up for me here? I dont get why my answer is wrong

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I used system of equations to get my quadratic equation

chrome ether
#

check your work

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you might have solved the system incorrectly

white rapids
#

I used points (1,6) and (2,1) because it seemed easier
So like:
a(1)^2 + b(1) + ~~c ~~= 6 --> a + b = 6
a(2)^2 + b(2) + c = 1 --> 4a + 2b = 1

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c's cancel out

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Multiply (a + b = 6) by 4 to cancel out one of the terms

4a + 2b = 1
-- (4a + 4b = 24)
-2b = -23
b = 11.5

Plug b into a + b = 6
a + 11.5 = 6
a = -5.5

Plug a & b into quadratic equation:

-5.5x^2 + 11.5x + c = y

Use one of the points to get c:
-5.5(1)^2 + 11.5(1) + c = 6
-5.5 + 11.5 + c = 6
c + 6 = 6
c = 0

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Equation is y = -5.5x^2 + 11.5x

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i really dont get it

willow skiff
#

so a + b = 6 is already wrong, the c doesn't go anywhere

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you have a + b + c = 6 and 4a + 2b + c = 1

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if you subtract both equations, you get -3a - b = 5

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you need another equation like with the point (6, -99), so 36a + 6b + c = -99

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see how you go from there

uneven dew
#

Hi, If we know a function isnt polynomial, exponential or logistical. Can we safely say its linear? The derivative of the function is always an integer ≥ 0

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And f is also an integer

elfin cargo
#

If the derivative of the function is always >= 0 then we know it is an increasing function

uneven dew
#

Not always > 0

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Always ≥ 0

elfin cargo
uneven dew
#

But = 0 isnt increasing

elfin cargo
#

If the function is linear then its derivative is always equal to a constant

elfin cargo
#

increasing can be 0 but strictly increasing is always > 0

uneven dew
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By linear, i mean when the scale at which this function is viewed at, is huge

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So these scenarios where f'=0 seem to disappear

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And f smooths out

elfin cargo
uneven dew
#

When you zoom in, it looks like increasing linear at some ranges, then constant 0 at some too

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Ik, but by linear i mean its a line, not parabolas or similar

elfin cargo
#

kind of like an illusion

uneven dew
#

Can we prove this illusion then

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Thats what am looking for

elfin cargo
#

No

uneven dew
#

Like, if we are given properties of this function. Can we prove that it will assume linearity as its domain increases

vapid plaza
#

What is “f is also an integer”?

uneven dew
#

...

elfin cargo
#

Does this count as spam?

uneven dew
#

Think so

vapid plaza
#

Anyway can you clarify what you mean

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@uneven dew

uneven dew
#

You know like how pi(x) is approximated with logs

elfin cargo
vapid plaza
#

Nah I don’t even understand the first thing he said

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What “and f is always an integer”

uneven dew
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f(x) is always an integer, f'(x) too

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Both share the same domain, x is in [0, ...⟩

elfin cargo
#

☠️

uneven dew
#

?

elfin cargo
elfin cargo
uneven dew
#

f(x), f'(x) = 0,1,2,3,...

elfin cargo
#

I mean $x \in \mathbb{R}$ or $x \in \mathbb{N}$ ?

obsidian monolithBOT
uneven dew
#

mainly N_0

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But we can accept and approximate the output of decimals too

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But as mentioned this is just an approximation

elfin cargo
uneven dew
#

I dont understand your statement, can you elaborate thx

elfin cargo
obsidian monolithBOT
elfin cargo
#

you need to find: $\Delta x$

obsidian monolithBOT
uneven dew
#

Thats true for x ≤ 2000. But i dont know how to prove it for the other values

elfin cargo
uneven dew
#

Condition for what

elfin cargo
uneven dew
#

Yea

elfin cargo
#

Is this a problem in your school? I am very confused

uneven dew
#

Nah, its just something am working on independently

viscid thistle
#

I wanna know if there’s a calculator that can solve all types of calculus problems for high school
Btw its not typical highschool calculus, alittle more advanced

uneven dew
#

Wolfram?

elfin cargo
#

It also has a computer algebra system like Wolfram

viscid thistle
viscid thistle
viscid thistle
elfin cargo
viscid thistle
#

i've got one

#

but it's in hindi

viscid thistle
#

its also 5 hours long , but what you are looking for is explained very clearly in it \

#

i can solve it but , im doing vectors and 3d rn

#

Imma watch what i need and get back to you, thanks man!

normal shadow
#

if im doing binomial expansion and the first variable has a coefficient, how do i do it

#

i tried to find some videos online explaining it

#

but nothing really shows up

#

any recommended vids??

chrome ether
#

you apply basic exponent laws

#

raise the coefficient to the appropriate powers as well

#

ex $(2x+1)^2=(2x)^2+2(2x)(1)+1^2=4x^2+4x+1$

obsidian monolithBOT
#

elrichardo1337

chrome ether
#

more explicitly, $(ab)^x=a^x\cdot b^x$

obsidian monolithBOT
#

elrichardo1337

normal shadow
#

is there a faster method to do this when you have a large exponent

#

I have to get the power to the ten

#

do i have to just do it by hand?

random yoke
#

Binomial theorem

normal shadow
#

yeah, like i mean

#

in the binomial theorem

#

how do i plug in the 2x for example

#

like where does the 2 go

#

in front of the "a" where a is to the power of n - k

random yoke
#

No

#

The 2 should also be raised to the power

#

You can imagine replacing 2x with another variable like u, and then substituting 2x back in once you've applied the binomial theorem

normal shadow
#

so i would go (u + b)^10, apply the theorem, get the final answer, and resubsitute "u" and 2x?

random yoke
#

Yes

normal shadow
#

and then just simplify from there

#

coolio

#

thanks

#

Is this right so far?

elfin cargo
#

<@&268886789983436800>

high venture
#

hello guys , i am stuck with this problem , so , someone can help me please it 's an EMERGENCY !! show that (n+1)*3-n is equal to the sum from 0 to n of 3-n pleaseeeeee 😦

uncut mulch
#

did you copy down the quesiton correctly?

#

that sounds wrong

uneven dew
#

Where a_n = 2, 1, 0, -1 ..., -(n-3)

uneven dew
#

And the sum S_n = (2a_1 + dn - d)*n/2

#

Then you could maybe continue from here and try forming equations and manipulating stuff

uneven dew
#

(5n - n²)/2 = (n+1)(a_n)
(5n - n²)/2 = (n+1)(a_1 + dn - d)
(5n - n²)/2 = (n+1)(2 - n + 1)
(5n - n²)/2 = (n+1)(3 - n)
(5n - n²)/2 = 3n + 3 - n² - n
5n - n² = (3 - n² + 2n) * 2
5n - n² = 4n - 2n² + 6
Might have done something wrong, but there exists some values of n where LHS ≠ RHS. Therefore the two sum formulars arent the same

prisma pewter
#

wait, it's all conics?

daring tapir
#

@fickle cedar

fickle cedar
#

,rotate

#

no

#

,rotate

#

there

#

is this readable?

daring tapir
#

Deleted

lusty harness
#

confused if this is wrong because ive checked on my calculator and im pretty sure the answer is b

chrome ether
#

wolfram alpha agrees with you

lusty harness
rigid cove
#

I’m pretty sure the answer is b

chrome ether
#

hmm b and c are equal

#

this is just a poorly made question

#

they want the expression obtained via half angle (ignoring that it can be simplified to the form shown in answer choice b)

rigid cove
#

oh huh

#

I see..

chrome ether
#

i think their "intended" answer is c then

viscid thistle
#

pls help me with this question . ([] means greatest integer function)

willow skiff
#

So the endpoints are x = 2 + 1/2 and x = 2 + 2/3

#

but it doesn't include 2 + 2/3, cause you get 3 + 3 = 6 instead of 5

viscid thistle
#

how many values of x did you get?

willow skiff
viscid thistle
#

ohh thats correct

#

pls can you elaborate it again

willow skiff
#

so 32 - 24 = 8

viscid thistle
#

how did you get those numbers?

willow skiff
#

x + 1/2 is always greater than x + 1/3
so [x + 1/2] has to be 3 and so [x + 1/2] has to be 2

that's the only possible way to make 5

viscid thistle
#

ohh ok

#

understood

#

but why not 4 and 1?

willow skiff
#

[x + 1/2] and [x + 1/3] can only be 1 apart as (1/2 - 1/3) < 1

viscid thistle
#

1 part meaning?

willow skiff
viscid thistle
#

but why??

willow skiff
#

Like keep trying different values of x such as x = 1/6, 1/2, 1/3, 2/3 if you're not convinced

#

cause you're rounding down, so if you have x + 1/2 and you add 1/3 - 1/2 = 1/6 to it

#

then you can cross a number, so x + 1/2 can round down to 2 but x + 1/3 can round down to 3

#

you can't have that x + 1/2 rounds down to 2 but x + 1/3 rounds down to 4

viscid thistle
#

i think i need to learn some maths

paper tartan
storm galleon
#

Why do we take infinity as 1/0 in limits

chilly plume
white elbow
#

I take 2/0

rigid cove
#

We don’t really take infinity as 1/0

proven night
#

Hello, guys

#

I need help

#

cos (10^x) = 0

#

My answer is x = log(pi/2 + pi*k), k is an integer

#

But

#

I doubt that k can be any integer. Because if it's a negative integer, then the argument of the logarithm is also negative

#

But it's beyond a log domain

#

So

#

Should i say that the answer is x = log(pi/2 + pi*k), but k is a positive integer including 0?

rigid cove
#

sure, so you could say $x = \log(\frac \pi 2 + k\pi)$ for $k \in \mathbb{Z}_{\geq 0}$

obsidian monolithBOT
#

Pseudonium

proven night
#

But photomath says the opposite

proven night
#

Is it just x = log(pi/2 + k*pi)?

#

Where k is an integer

proven night
willow skiff
proven night
willow skiff
#

they've split the list up as (pi/2, 5pi/2, 9pi/2....) and (3pi/2, 7pi/2, 11pi/2....)

proven night
#

I mean they say that k is any integrr including negative ones

willow skiff
#

if you have a complex logarithm then yeah those solutions aren't correct, you would need to be adding on multiples of 2pi i / ln(10) as well

elfin cargo
#

yeah, complex variable will solve the problem

willow skiff
#

so yeah PhotoMaths doesn't understand maths logic

elfin cargo
#

Oftentimes, math software will give you solutions in complex domain

proven night
#

I dont know what are complex logarithms, sorry, so what's the final answer without those complex logarithms

elfin cargo
proven night
#

Okay, thanks. But are those complex logs learnt in high school?

elfin cargo
proven night
elfin cargo
obsidian monolithBOT
#

Closer

elfin cargo
#

to find value of k

rigid cove
#

this is just $k \geq 0$ anyway

obsidian monolithBOT
#

Pseudonium

rigid cove
#

cause k is an integer

proven night
#

Okay, thanks, i just want to clarify everything so that i have a solid understanding of it

rigid cove
#

mhm

proven night
#

And i am struggling with this equation

#

I tried using logs on both sides

#

But i think that after that and applying square of sum formula i only complicated this

elfin cargo
#

so you have this: $ln(3^{\sqrt{10-\sqrt{x}}}) = \frac{3}{2} ln(10-\sqrt{x})$

viscid thistle
obsidian monolithBOT
#

Closer

proven night
elfin cargo
#

😂

proven night
#

Maybe i should let 10-√x be t

proven night
elfin cargo
#

From that I can make it to this: $\frac{2}{3}ln(3) = \frac{ln(10-\sqrt{x})}{ln(e^{{\sqrt{10-\sqrt{x}}}})}$

obsidian monolithBOT
#

Closer

elfin cargo
#

I don't know how to simplify it further breadthink

daring tapir
obsidian monolithBOT
#

Ender Doesn't Mind

daring tapir
#

now we can divide by 2

#

and we see that both are of form ln(t)/t

#

hence by simple comparison

#

sqrt(10-sqrt(x)) = 3

#

ie x = 1

#

but there is probably a much more formal proof

proven night
#

Thanks

#

By the way why ln x^c = c * ln |x| when c is even?

#

Is it because √a^2 = |a|?

proven night
daring tapir
daring tapir
proven night
#

But when c is odd, we left x as x, but not as |x|, because x^c (c is odd) cannot be negative in logarithm by default?

#

I mean is it a reason why this rule doesnt apply to c when it's odd

daring tapir
proven night
#

Okay, i understand it

elfin cargo
#

Ah, nvm

proven night
#

Can anyone help with it?

#

I need to factor it, but ln |x| and ln x are different, right?

willow skiff
# proven night

Note that you can't have x < 0 however, cause ln x would be undefined

dire locust
#

hoi

willow skiff
#

so all your solutions must have x >= 0 cause of the RHS only being defined for x >=0

proven night
#

So what should be done next?

willow skiff
#

so you can remove the absolute value

#

4 ln x - ln^3 x = 0 and now set ln x = u

proven night
#

But i dont understand why we can remove absolute value

willow skiff
proven night
#

i still dont understand why rhs matters

willow skiff
#

so (ln x)^3 wouldn't be defined either

proven night
#

So you're saying that x cannot be negative by default since we have this RHS?

proven night
#

So there is no need to use abs value

willow skiff
#

yeah so if there are any solutions, they must all satisfy x >= 0

#

and so you can drop the | |

proven night
#

But if it was 4ln |x| = 0, we wouldn't be allowed to drop the abs value?

#

Cause x can be any number

willow skiff
#

you'd be better off doing ln(x^4) = 0 implies ln(x^4) = ln(1) and then ln is 1-to-1

proven night
#

Okay, thanks, i got it

willow skiff
#

np

elfin cargo
obsidian monolithBOT
#

Closer

elfin cargo
#

Absolute is really annoying

willow skiff
#

you can't just drop it randomly

elfin cargo
#

I saw this a lot in textbook, though

willow skiff
elfin cargo
#

But setting conditions like this will not give you a general solution

willow skiff
#

I mean it gives you all solutions in the real numbers so

elfin cargo
willow skiff
elfin cargo
sour phoenix
#

please why is it that when you use the u-substitution in an integral like this:

Int(1/x^2(root of x^2-(9))

It doesn't work??

raw hill
#

because it doesn't? (at least w/ the substitutions you've prob tried)

#

if you substitute u = x^2 or x^2 - 9

#

du = 2x dx

#

you don't have a factor of x

#

hence it doesn't work

sour phoenix
#

ohh yeahhhh

#

It's either using à trig fxn or factorisation

Like setting x=asectheta

Or just factor out .

raw hill
proven night
#

Hi

#

I am totally clueless what i must do to solve it

raw hill
obsidian monolithBOT
#

Civil Service Pigeon

raw hill
#

Now, consider what identity relate sin and cos

#

You should think of ||the Pythagorean theorem||

proven night
winter comet
shadow ether
#

oh wait

#

old prob

#

nvm

white elbow
#

Right, you don't need abs, strength is more important these fitness freaks making abs overrated

flat shuttle
#

Which average rate of change is greater -0.04 or -0.4?

ivory vale
#

-0.04

flat shuttle
#

yeah I'm sure that generally -0.04 is greater but when a question says which has greater rate of change wouldn't you say -0.4 because it changes the most?

ivory vale
#

Oh,yes yes my bad.

flat shuttle
#

Ok thank you

normal yoke
#

Can someone help me with these

ivory vale
normal yoke
#

So i kind of skipped them

ivory vale
#

You should then first get a grasp on the graphs of quadratic functions

#

Are you an 11th grader?

normal yoke
#

10th

shadow ether
#

remember k is the y intercept

#

so find the y intercept of -x^2+3x

#

and use that for the others

daring tapir
#

<@&268886789983436800>

viscid thistle
#

I'm just joking..

slender river
#

Hurb

viscid thistle
#

sorry alr

slender river
#

lets not please, thanks

viscid thistle
north nebula
#

It will be C or D?

subtle wren
#

try them out

#

like say try x=-2 and x=2

viscid thistle
viscid thistle
subtle wren
#

sorry

viscid thistle
#

and the square root inside is only defined when 6-3x is non-negative

#

this leaves you to solve for values where 6-3x is positive

subtle wren
#

basically you can see that $\sqrt{6-3x}>0$, you can say that $6-3x>0$, so $6>3x$, then $2>x$, if you srebt sure its absolure or not, just try a number where one is correct and the other isnt, so for example -3, you can see that the value is valid

obsidian monolithBOT
#

Skill_Issue

north nebula
#

But someone wrote thus

subtle wren
#

i think they are wrong

viscid thistle
#

Yes

willow skiff
#

,w 1/sqrt(6 - 3x) Maclaurin series

obsidian monolithBOT
willow skiff
#

This is calculus @north nebula

north nebula
willow skiff
viscid thistle
willow skiff
pastel swallow
# north nebula

With this question about the conversion, the general rule is that x< absolute (1) right?
But is there an expansion where x doesn't have to be in that range?
It feels a bit useless having an expansion that is only valid for such a small amount of x values right?

willow skiff
#

that's the largest possible domain that it converges

pastel swallow
#

But if we use for example (1+2x)^-1
Then we would use this formula if im not mistaken
We would have to say The absolute value of 2X is < 1, but couldn't there be greater values for x than 1/2 that would still yield answers?

#

would the answer we get from above formula be plain wrong if x were to be greater than 1/2

summer ruin
#

you can just google whether the series for (1+x)^{-1} converges for x >= 1

summer ruin
#

you can't just always say |x| < 1

pastel swallow
#

I have this alpha mathematics book, I hope im understanding this right

#

so i think if there is (1 + (X) )^-1 then whatever is in place of X, that sould be < 1

viscid thistle
#

How do I differentiate

#

X^2ln(lnX)

#

Can anyone just me me what to do with the ln(lnX) part?

#

I am very confused

winter comet
viscid thistle
#

Ahhhhh

#

That makes sense

#

Hold up

#

Tell me if it's correct

viscid thistle
#

Chain rule???

winter comet
#

yes...

viscid thistle
#

But how can I use that here?

#

Wouldn't product rule be better?

winter comet
#

for ln(ln(x))?

viscid thistle
#

No

winter comet
#

or for x^2 ln(ln(x))

viscid thistle
winter comet
#

yes you have to use the product rule for the entire thing

#

but you asked "can someone just tell me what to do with the ln(ln(x)) part" and you have to use the chain rule to differentiate that

viscid thistle
winter comet
#

yeah

viscid thistle
#

I thought I had to differentiate them separately

#

Anyways lemme see

winter comet
#

i mean you will eventually differentiate ln(ln(x)) and use it in the formula for the product rule

viscid thistle
#

Uhhh

#

I am faced with a little problem

winter comet
#

what is the problem

viscid thistle
#

I used product rule

#

I got

#

X^2 * 1/x +2x*lnx

winter comet
#

you did sum wrong lol

viscid thistle
#

But how can I multiply 2x and lnX?

winter comet
winter comet
viscid thistle
#

Btw it's lnx

#

Not lnX

#

That was my keyboard auto correcting me

winter comet
#

d/dx x^2 ln(ln(x)) = x^2 * d/dx [ln(ln(x)))] + 2x * ln(ln(x)) by the product rule

#

right

viscid thistle
#

Yes

winter comet
#

d/dx [ln(ln(x))] = 1/ln(x) * d/dx ln(x) = 1/ln(x) * 1/x = 1/[xln(x)]

#

right

viscid thistle
#

Ahhhh right

winter comet
viscid thistle
#

That makes sense but didn't make sense at first

winter comet
#

yea

#

the nested ln are a lil trippy lol

viscid thistle
#

So that's where I made the mistake ig

#

I did

#

A d/dx B + B d/dx A

#

But I took A as x^2ln

winter comet
#

😭

#

ln is a function

viscid thistle
#

Yea

winter comet
#

ln(ln(x)) is like f(g(x))

#

and xf(g(x)) is not xf * g(x) like its not multiplied

#

its a function of

#

doesnt really maek sense to do :l

viscid thistle
#

Yeppie

#

Imma start functions after I am done with differentiation 2

winter comet
#

😭 😭 😭

#

bro is doing it in the wrong order 😭

viscid thistle
#

Am just doing the hard stuff first then imma start with the easy stuff

#

Oh right

#

Another problem....

winter comet
#

the chain rule is literally differentiating a function

#

a composite function

viscid thistle
#

I got x^2 * 1/lnx + ln(lnx) *2x

#

From which

#

I did

#

x^2/lnx + 2xln(lnx)

winter comet
#

x^2 * 1/ln(x) should be x^2 * 1/(xln(x)) -> x/ln(x)

#

otherwise its right

viscid thistle
#

Yeah it did come as x/lnx

winter comet
#

ok

viscid thistle
#

But can you explain the middle part?

#

Like x^2 *1/ xln(x)

winter comet
#

wdym

#

oh i meant

#

x^2 * 1/ln(x) is wrong, its actually x^2 * 1/ xln(x) which simplifies to x/ln(x)

viscid thistle
#

But why though?

winter comet
#

the derivative of ln(ln(x)) is 1/ln(x) * d/dx [ln(x)] = 1/ln(x) * 1/x = 1/xln(x)

#

chain rule

viscid thistle
#

Ye

#

Ohhh

#

Alright

#

So it has to be differentiated till there is no ln left

winter comet
#

i mean there is still an ln left

#

in 1/xln(x)

viscid thistle
#

Ehhhhhh

winter comet
#

you just have to use the chain rule :l

white rapids
#

Can somebody help me explain the symmetry here

#

x^3 - 4 also looks symmetric but also x^4 - 4 when i plug it into desmos

#

Whats the difference here

whole void
#

x^4 - 4 is not symmetric

burnt yarrow
#

could someone explain to me how this equation matches up with the graph e and not graph d?

uncut mulch
#

why do you think it should be d

burnt yarrow
#

because the asymptotes lined up

#

but i know it’s e i’m just confused

uncut mulch
#

asymptotes are the same for botg

burnt yarrow
#

yeah so like how can i tell the answer 😭

uncut mulch
#

sub in a few x coods for points

#

to see which section the curves will be in

#

e.g for something between the asymptotes
what happens when x=3

burnt yarrow
#

ohhh

#

okay that’s smart

#

thank you

white rapids
#

Its symmetric on both sides

visual pier
#

Hi guys, I'm having trouble with arithmetic, does anyone have a book to recommend?

whole void
white rapids
whole void
#

wdym?

white rapids
#

Ok,

#

So like on a quartic or a quadratic it goes to infinity for either -infinity and infinity on the x axis

whole void
#

what is x^4 - 4 symmetric about

white rapids
#

I really dont know

#

Explain to me

whole void
#

what is y = x^2 symmetric about?

white rapids
#

????

whole void
#

why the question marks?

white rapids
#

Because I dont know man

#

If you could explain that'll be great

#

If not i can just ask someone else

whole void
#

without looking it up (cause if u dont know i can explain it better) what does it mean for something to be symmetric

whole void
#

in terms of shapes and geometry, more specifically

white rapids
#

Equal in size??

whole void
#

no

#

do u want me to explain?

white rapids
#

Yes

whole void
whole void
#

sorry my parents kept bothering me

#

a shape/curve/graph is symmetric about a particular point/line (etc.) if for every point on that graph, the reflection of that point about the point/line of symmetry yields an image that also lies on the graph

#

try to understand this

#

@white rapids

whole void
#

its called the axis of symmetry of the parabola

#

heres a quick sketch of this

white rapids
#

Right

#

So why cant a quartic function be symmetric even though at the same x value, its 2 of the same y values

whole void
#

what is y = x^4 - 4 symmetric about, if anything?

white rapids
#

Lets say

whole void
#

and why

white rapids
#

For x^4 - 4, for 1.25 and it's reflected x value, and we plug it into the function

#

Both the x value and its reflected x value, are the same y value

#

Both points are equidistant from the axis of symmetry

white rapids
#

It doesnt have to be x^4 - 4 but literally any transfomation or shifts it has

whole void
#

what is x^4 - 4 symmetric about?

white rapids
white rapids
#

Reflected x values, same y value

whole void
#

that doesnt answer my question what is it symmetric about

white rapids
#

For any reflected x value, it'll be the same y value

#

It has the same reflected image whether its going x negative or positive infinity

whole void
#

that still doesnt answer the question

#

what is x^4 - 4 symmetric about

#

@white rapids

white rapids
#

Its equidistant from axis of symmetry from both points

#

I can keep going

whole void
#

u r never answering the question i dont know why

#

what line/point/shape is the graph of x^4 - 4 symmetric about

white rapids
#

@winter comet

whole void
#

can u answer pls?

winter comet
#

yo

white rapids
#

Im not sure if im misinterpreting this

winter comet
whole void
#

they wouldnt answer

white rapids
#

Axis of symmetry i thought i said that

whole void
whole void
winter comet
#

symmetric about a point i'm pretty sure means the same distance, 180 degrees away

winter comet
#

except about a point instead of a line but yeh...

whole void
#

it can be either

winter comet
#

thats why the odd function reflects about the point and the even function doesn't

whole void
#

an odd function is specifically defined to mean symmetric about the origin i.e. a point

#

but im pretty sure u have heard of lines of symmetry in a square for example

white rapids
#

Do I gotta look at the z axis or something

whole void
#

z axis?

#

its just a reflection over the point

winter comet
winter comet
#

this is all just 2 dimensional

whole void
white rapids
#

I still dont understand

whole void
#

why

winter comet
whole void
#

what dont u get

white rapids
#

Are we looking at x = 0 to know whether it determines

whole void
#

no

winter comet
#

otherwise x^4 - 4 would be correct

whole void
#

it says a point not a line

#

why is x^4 - 4 not symmetric about (0, -4) @white rapids and not vicious viper pls answer this

white rapids
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Because

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Its not at y = 0

winter comet
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"Because"
-greatest answer