#precalculus
1 messages · Page 269 of 1
egocarpo:
No
ah then we need to modify
how hard is skipping pre calc
Positive
No
okay
,w plot -x^2
This one has a max point at (0,0)
okay so we want the sign on the x^2 term to be negative
yes
f(x)=-x^2+bx+c we have now 🙂
lets see if we can find a b and c so that it f(-3) is equal to -6
f(-3)=-6 this is what we want
Ok
$f(-3)=-(-3)^2+b(-3)+c=-6$
Mhm
egocarpo:
oh we need it to be the max point aswell
hmm have you shifted functions before
like if you look at f(x) and then at f(x-1)
No?
We are working here wait for your turn 😛
I don’t think so
k.
The graph shifted
Mhm
,w plot -x^2-6
?
The Max is (0,-6)
(-3,-6)
do you remember how we did to shift the all the points of the function? 😄
Yes
f(x)=-x^2-6
For this we have to move to the left 3 times a
this has a max at (0,-6)
and yes we want to move allt points three steps to the left
so when we took f(x-1) we shifted to the right
so if we take f(x+1) we shift to the left
,w plot -(x+1)^2-6
,w plot -(x+1)^2-6
Ok cool
and then if you write on in standard for you have to simply it
-(x+3)^2-6, write this out on ax^2+bx+c form
there is a square
Yes I put that
$-(x+3)^2-6=-(x^2+6x+9)-6$
egocarpo:
So would you have to do 9-6?
So the answer will be -x^2-6x-15?
that is one answer
there is infite solution 🙂
This is how I would view it there might be smarter ways to go about it!
So I should put -x^2-6x-15?
I mean do you think it fits the description?
I think so
it it a quadratic function with max value at (-3,-6)
Imma put it in the calc.
Good do that to be sure
How do I find the max?
Have you done derivatives?
Yeah
you can just plot it between some x-values around x=-3 and see if it is a max
If you are asking you probably need it
khan academy explains it well
yeah and I said if you ask that question then you should probably do it
I'll ping u later nvm
haha don't
im interputing
And yes you kinda were, you need to wait on your turn, and I dunno if you should skip it...
@opaque idol are u able to work it out?
@burnt sonnet so u
since jpiggy is not here for now
May I ask why I shouldnt skip pre calc
I mean I did most of the khan academy course
If you felt safe about it you wouldn't ask
and it seemed pretty easy
I don't even know what this is we don't do that in my country 😛
bruh
wait where do u live
europe 😄
Maybe try and take some online test for it and see if you know it well enough
yes
Ye that is good for further studies
Not sure if i did this right...
is that $y = x\csc(x^2)$ or $y = x(\csc(x))^2$?
Ann:
Im assuming csc(x^2)
half these n's are horribly written
$\lim_{n \to \infty} \sqrt[n]{n}$ is this what you want the limit of?
Ann:
write $n^{1/n}$ as $e^{\frac{1}{n} \ln(n)}$
Ann:
alright and then what
$\frac{\ln(n)}{n} \to 0$
Ann:
e^0 isn't 0
yeah it's 1
Is anyone good with piecewise function, i somehow got this problem right 2 weeks ago and somehow forgot how to solve it :)...
Nvm i got it
1-sin^2\left(\frac{7\pi }{6}\right)
Hello, can someone explain to me why n=8?
Try to write i in the form of e^{ix}
Could anyone help me with the first part of this question?
Yeah @willow bear
thing is I don't really know how to do that, I can use differentiation of first principles to differentiate but that's about it I don't know about X or y cords ;-;
...
ok so like this is way too early for differentiation
are you... telling me you don't know anything about the coordinate plane??
dnusbaj nononono, I just don't understand how to use differentiation to find the y cords
I'm not?....
A lies on the curve y = x^2 - 6x + 5 and its x-coordinate is 2. what is its y-coordinate?
so what is it then
-3
there we go
B also lies on the curve y = x^2 - 6x + 5 but this time its x-coordinate is (2+h).
what is B's y-coordinate?
(4+2h+h^2) - 6(2+h) + 5
h^2 - 2h - 3
ok great
so A and B have coordinates (2, -3) and (2+h, h^2-2h-3) respectively.
are you able to find the gradient of AB?
mhm
I think
Y - y1 / X - x1
but how do I do this when I've got h terms?
-3 - H^2-2h-3 / 2 - 2+h
ifkhnjfdlksjhfkj
okay so there are several things wrong with this
most starkly the absence of parentheses and the random capitalization
why not write $\frac{(h^2 - 2h - 3) - (-3)}{(2+h) - 2}$
Ann:
yes it can
it can be simplified plenty
and in fact SHOULD be.
@fickle plaza sorry for the delay, had some irl shit to attend to
Anyone know how to solve this $ \frac{3^{3-x} } { (3^{3-x} ) + 3^x } = .5 $
pancakehammer:
I think I reduced it to $ \frac {3^3 } {3^3 + 3^{2x}} = .5$
pancakehammer:
but not sure what to do here
Al𝟛dium:
$27=\frac12 (27+3^{2x})$
Al𝟛dium:
pancakehammer:
$ 27 = 3^{2x} $
pancakehammer:
Yeah
now is where I confuse
From here you can do it by logic/trial or just log properties
how would you use log properties
Al𝟛dium:
yo this actually makes sense how logs work now
Can someone help?
@opaque idol what have you tried
Have you got anything?
Yeah
Or how to get f(x+4)
Not sure how you got there
Say we have h(x)=x-3
Then h(👀 )=(👀 )-3
h(🍞 )=(🍞 )-3
h(71863849916)=(71863849916)-3
h(x²+x)=(x²+x)-3
Does this clarify it
Wym
It's an analogy i use to make you understand that whatever is inside the parens on h(x) is gonna be plugged into the x
As i did with the bread, the eyes, the number and the x²+x
Do you understand what i did
Oh ok I get it now
Oh can you get f(x+4) by yourself then?
Yeah?
i'm not getting that exactly
What did you got for g(x) first
Like the expression of g
I think (1,3)
No like the function g
Oh
Would u plus in x^2-2x+3+4?
Wait so
Say we have h(x)=x-3
Then h(👀 )=(👀 )-3
h(🍞 )=(🍞 )-3
h(71863849916)=(71863849916)-3
h(x²+x)=(x²+x)-3
Remember this
I got it from the g(x)
Don't be sorry
So
If you have f(x)=x²-2x+3
Find f(x+4)
Let's do this step by step
Forget about g for now
And focus on that ^
What you want to do is to plug x+4 into all the x you see at x²-2x+3
What do you get
Ok
Al𝟛dium:
Now we get into the obscure world of algebra
Remember that (a+b)²=a²+2ab+b² and NOT a²+b²
Try to simplify that
@opaque idol
(X+4)^2-2x-8+4
Yes
So far so good
Expand (x+4)² now
@opaque idol ???
Do i have to ping you?
For you to answer?
That would make it (x+4)(x-4)
@opaque idol how?
(x+4)² is (x+4)(x+4) on any case
But why not just use $(a+b)²=a²+2ab+b²$ instead of expanding (a+b)(a+b)
Al𝟛dium:
Alright i'm tired of waiting and getting ghosted. I'm out unless you change your attitude.
No. Jpiggy
o
Could any of you help me get the flow of how this works, I've studied it before but it's been years so I've forgotten
As in the steps you take to solve it
I'd love to google myself but I'm not quite sure what to google about it
so you've got a composite function
Meaning, first, you need to find the inverse of f(x)
This algebra 2 and precalculus video tutorial explains how to find the inverse of a function using a very simple process. First, replace f(x) with y. Next, switch x with y. Finally, solve for the y variable and that's it. This video contains examples and practice problems ...
why not just apply the definition of the inverse
This algebra video tutorial provides a basic introduction into composite functions. it explains how to evaluate composite functions. This video contains a few examples and practice problems.
My Website: https://www.video-tutor.net
Patreon: https://www.patreon.com/MathScie...
Thank you, I didnt see someone answered
Thanks a lot
i got −5^√5 for the inverse of x^5-3
correct?
Whats that?
$f(f^{-1}(x)) = x$
ramonov:
But you still have to do the inverse and do a composite function right
nope
but you should deduce that an inverse actually exists for that function
i wish i was taught that too lol
split it up and write tan^2x as 1+sec^2x and it will simplify down but yeah wrong channel
@steady seal do you still need help?
how do i approach this
@steady seal 5-5sin^2theta = 5 (1 - sin^2 theta)
@fossil locust try not to just give the answer if you can 🙂
@lament fiber you will get DNE
yeah I was about to correct that sorry
it's been a while since I've done this I'm basically starting over
lim sin x/x =1
lim tan x/x=1
I think it'll work
yes it should
as x approaches 0 lim sin(x)/x=1
small angle approx is the same thing
@lament fiber I just did it on paper, it's actually indeterminent
because tan(0) = 0 and sin(0) = 0
yeah you're right
divide top n bottom by x @viscid thistle
you'll get 0/0 then
I suggested the same thing
(1-1)/(1-1)
@serene heath
and they aren't supposed to use l'hopital
also can someone help me in #help-0
I asked here but it got ignored like my prev question so I removed it from here and stuck it in questions and even pinged the Helpers twice 
@lament fiber are you still stuck on that limit?
divide top n bottom by x @viscid thistle
@serene heath
U'll get 0/0
it was @viscid thistle ‘s question @viscid thistle
\frac{x^{2}}{4}-\frac{\left(y-3\right)^{2}}{5}=1
You can input this into desmos if you want. Why is there a hole at y = 3 for the vertices?
for all $ A,B \in \mathbb{R}^{+}$ such that $A \neq B$, and that neither $A$ or $B$ are $1$, and $\log_{A}B = \log_{B}A$. Find $AB$
the problem is that if you let $n = \log_{A}B = \log_{B}A$ then $A^n = B$ and $B^n = A$. Therefore $AB = (AB)^n$ and here $n$ can only be 1. But that means that $A = B$
any ideas?
oh nvm im stupid
did i go overboard here or did i do it right?
You're taking the square root of both sides which should give sqrt(9π) not sqrt(9)π
@warped dagger
Okay, what do you mean by that?
alright, may i know why? it just kind of doesnt make sense to me
because pis cancel out?
Exactly
Pi is still a number
Imagine it was x
If u have 18x/2x it would be 9 not 9x
Similarly 18 pi/2pi is 9 not 9pi
i see, thanks.
Np
was there anything else that i did wrong there?
I don’t believe so
Yeah other than r=3 I think ur fine
However
If in some scenario u did in fact end up with r^2=9pi, r would equal 3*sqrt(pi) not 3pi
@warped dagger ^ sry for tag, responded late
What did u get for a?
Yeh bro I can’t help u cause I’m dumb but I think since it’s been 15 minutes you can @ the helpers
<@&286206848099549185> I need help with the trig question
someone i just can't get sin - cos by itself
Anyone has any idea how to even start?
Yes almost done
I can't get a hair out of this problem
Change tan and cot into terms of sin and cos and then common denominator
Try from there
I got $\frac{sin^2x+cos^2x}{sinxcosx}=8$
chene12:
Yep and what does the numerator equal
1
well i got $sinx=\frac{8}{cosx}$ and $cosx=\frac{8}{sinx}$
chene12:
well adding them directly wont do me any good
Keep the sin and the cos together
how so?
Sinxcosx=1/8
This one requires a bit of creative thinking . Can u think of anyway possible to get a value sinxcosx
Utilizing not only ur first equation, but ur second one too
not sure
I’ll give u a hint, it has to do with squaring the second expression
chene12:
I think u missed a part of the term in the middle but that’s alright, I was referring to the sinx+cosx
How could u get sinxcosx from that
something to do with $1+tan^2x=sec^2x$ and $1+cot^2x=csc^2x$?
this latex rendering speed is slow 😦
Hm
chene12:
im guessing something to do with these?
Not really. Think back to the sin x + cosx part
Strictly from that expression
What operation would u perform on that expression to give u sinxcosx
oh you can convert tanx and cotx into its sines and cosines
Nahnah just try this: What operation would u perform on that expression to give u sinxcosx
Multiply, add, subtract, exponent, log? What would give u sinxcosx
multiply?
$cos^2xsin^2x$ to cancel out the denominators of tan and cot
chene12:
right?
Hm
How would u use an exponent to get there tho
What is the simplest exponent that we know?
square
The one that we learned first, other than 1
Exactly
Try squaring it
See what u get
By it, I mean squaring sinx+cosx btw
Wat is the inverse of f(x) 5x-2
substituting cosxsinx with 1/8?
Wat is the inverse of f(x) 5x-2
Sure, and how about the first two terms?
which is 1
Yep so what do we get
1 + 1/8
Remember it’s 2(sinxcosx)

Leave it in fraction form, what’s the left side of the equation?
not sure
How did u end up with sin^x + cos^x + 2sinxcosx
(cosx + sinx)^2
Exactly
then take square root?
U got it
yay thanks
Yooo noice
Wat is the inverse of f(x) 5x-2
$sinx + cosx = \frac{\sqrt{5}}{5}$
chene12:
Bro derp u gotta wait for chene to finish being helped and then can I get help cause I’ve been waiting for and hour
So (sinx+cosx)^2 = 5/4
Yes exactly
But what happens
When u take sqrt
Think abt the signs
$\pm 2$
chene12:
$\frac{ \sqrt{5} }{ \pm 2 }$
chene12:
thanks
Np
Bro I keep making absurdly wrong one’s. This may be too large of a problem but I would really appreciate some help
I need to make 2 rational functions that meet those requirements
Scout I can give u a 2 minute explanation for the first one then I gotta go man
Yeh anything helps
Well it’s a hole
Yup, but how does it occur
U get it when you can factor out of the numerator and denominator
Exactly
Like if u have (x+4) in the numerator and denominator
x(x+4)(x-8) over (x+4)(x-8)
Ok yeh
Yee
How do u get a vert asymptote
Yup, but specifically changes made to the function
Well
Remember that those are the holes
So they can’t be the inf discontinuities
U would have to make up 3 more
Um
7?
I figured out what x could equal that would make the denominator equal to zero
Bingooo man
So what would u do to the original equation with the holes in it already
K imma write it real quick
just write the final expression i wrote
so how could we finish it up
based off what i did
Well the numerator would be x^3-4x^2-32x
Ok
To the numerator
nahh cuz we tryna do vert asymptotes which always go in denominator
K
so what would u do
No clue
how do u get a vert asymptote again? refer to what i did with 4/(x-7)
nope, cuz -4 and 8 are already holes so we cant use them for infinite discontinuites/vert asymptotes
we gotta create new ones
Division?
and u need 2 more new ones
i mean, we just put x-7 in the denominator to get an asymptote
so what would we do to get 2 more
Hm
Make more idk
Yes
Oh ok Yee
So (x+6)
And (x-2)
Bro that took me too long to figure that out lol
Lol
Just take picture of what u wrote for final expression
Just to make sure u got it
Does ur teacher demand u to simplify?
Cool awesome
Yee
Try plugging it in to see if it’s right
I also got my TI-84
Shoot I wrote it wrong
Cya
Tap on the places where ur supposed to have holes
It should say “undefined” for the y values @livid fjord
To find the oblique asymptote I think I’m doing the division wrong
where's your quotient?
also there won't be an oblique asymptote here.
Ah okay thank you
your therapist
Can someone do it fast to see if it's -inf.
I have -inf but in my textbook I have +inf
,w lim as x approaches -inf of (sqrt(x^4-3)-xsqrt(9x^2-1))/(2x+7)
Sqrt(x^4) is always +x^2?
,w lim as x approaches -inf of (sqrt(x^4-3)+xsqrt(9x^2-1))/(2x+7)
It's inf, thought so I rechecked it and it's inf not -inf
Sqrt(x^4) is always +x^2?
@cedar pawn yeah
Same for any even exponent except for 2?
hello yall, im struggling with this question here
ive tried a multitude of things including whats in the answer box atm and i cant seem to pin down the answer
huh
how can the cosine of any real number be -6
also thats not how the double angle formula works
cos(2x) is cos^2(x) - sin^2(x) not 2cosx
so ig the last one
yeah looks right
@viscid thistle what made you say 65?
@viscid thistle what made you say 65?
@proud raven 65 is the right answer
but idk how you get it
properties of arc length
properties of arc length
@uncut mulch great explaiantion
Anyone that can me with this problem please
@vapid gate SOH CAH TOA
Are the two problem solving Sin and Tan @velvet granite
Well, you need to use the identities to solve for the missin sides
You have the angles 61, 90, and whatever 61+90-180 equals as your third angle
WELL i have x already but struggling witth y
Thanks
np
so 8.87^2+ 16^2 = y^2
I did it by using the sin found it much easier but thank you so much!
hello does anyone have answer key to math 1103 precalculus spring 2016?
course content is different everywhere
mirzathecutiepie:
since $180-\theta$ can be the angle between the x axis and the 6m vector as well, and from there we use the identity $cos(180 - \theta) = -cos(\theta)$
mirzathecutiepie:
if so, which one is "correct"? Do we solve for both angles and say hey I want an obtuse one so I'll choose the largest one?
@rugged linden Because the angle lies in a quadrant where the "x" value is negative, or where the angle > 90, (cos(angle) = x/r after all), the only value that would be appropriate in this case would be where x < 0, so 2/3 would not be a solution here
same reason you can't cancel out the fives in $\frac{5-2}{5}$ to get $-2$
ok texit is dead
lemme just handwrite it
Ann:
ah there it goes
help
for a It says a has to be positive and for b a has to be negative
@velvet granite @quartz oxide
https://media.discordapp.net/attachments/773215149535526962/773645132968755240/image0.jpg?width=508&height=677
for this how can i fit the 12 years on the x axis
@velvet granite ok but how do i make the graphs
Treat the years starting from1996 like x values
Number of adult animals like your y values
How do I find the maximum angle that I rotate f(x)=(3x^2+x+3)/(x^2+1) such that f'(x) is still a function, where f'(x) is the new equation after rotation?
I feel like it has something to do with injectivity, since the rotated function needs to pass the vertical line test
So I found that the function is injective on (-infinity,-1) U (1,infinity) and (-1,1), but I'm unsure how to use that info.
probs try asking in a different channel
in what channel
should be correct
yeah looks good
i got 8,28,88
how do i solve this
says minimum height of bridge over road is 4 but how is that relevant, the height is already 5
highway road is 10m wide which only gives 5 on each side, still dont know
you're dividing by a quadratic, so the remainder is a polynomial of degree at most 1
so you have: P(x) = (x+4)(x-3)Q(x) + ax + b
where ax + b is your remainder, and a, b are constants that you need to find
@uncut mulch the other person is actually posting my working out
I posted the question originally on a different sever titled "Homework Help"
and he posted my question to this server before I did
he then messaged me to join his server
This is a bizarre conspiracy, wth
Not cool tbh for him to copy Ram's help and pass it off as his own
How do I do part a?
@viscid thistle so look
for example which % of students take a postgraduate degree?
👻
t!goal claim
What does it mean to raise something by a decimal? 10^4.640878 = 43740, but what does it mean to raise something by a decimal? To raise something by 4, sure, 10^4 is 10,000, but how do you wind up with a number like 43740, a very "unsquare" number?
so
for ur case
its 10^4.640878 right?
so 10^4.640878 is the same thing as
10^(4 + (640,878/1,000,000))
if we simplify that mixed fraction we get
10^ (4,640,878/1,000,000)
and then think about it like this
if 9^(1/2) is the same thing as √(9^1) with an index of 2
similarly
10^ (4,640,878/1,000,000) will be the millionth root of 10^4640878
The beginner understanding of exponents as "this number multiplied by itself this many times" just won't apply anymore, huh?
i guess
i see your steps, and thank you for that, but intuitively, 10^x in my mind should make a number that ends in many 0's. But you can put a decimal in x, any decimal into x and get any number you'd like out of it. How does that happen?
alright, so im not entirely sure abt why it happens, but we can also represent it utilizing logarithms
for example
10^x = 506
this means that log 506 = x
plug in into the calculator and u get 2.70415051684
then go back to ur original equation 10^x = 506 and plug in 2.70415051684
u should get 506
are those irrational numbers, those decimals?
i dont think so, given the fact that the answer comes out exactly to 506. and plus just think abt it, if u were to plug in a number with decimals that never ended, the final answer would never end either right? but the answer we have, 506, is a rational number that ends
i may b wrong, but thats what i think is right
I'm having a hard time learning logs, exponents and square roots. They all seem like different ways of expressing the same thing. How did you learn all those identities, just with sheer willpower?
i mean, i just think about it like this. For squares, ur just multiplying a number/variable by itself. That was just memorization. For integer exponents greater than 2, i just remember once again ur just multiplying that number by itself however many times the exponent is equal to. For exponents less than 0, u just do the same thing as the exponents greater than 2 except u gotta take the reciprocal. For numbers and variables raised to the power of 0, its just memorization that the answer comes out to 1.
square roots mb
o
sqrt of what types of values?
perfect squares? non perfect? variables?
but for logs its just memorization imo
the basic concept behind them
stuff like this
i mean, that right there is just a bit of creative thinking
i don't understand what's going on step by step
Step 1: problem. Step 2: tries to convert the denominator of that fraction into a value that can be inputted into the larger sqrt expression adjacent to it. Step 3 (tricky step): because u can combine sqrts, he puts them together under the radical. Step 4: simplify by factorization and by splitting up the fraction
Step 3 is a bit tricky
I'll give u an example
lets say u have (1/3) (sqrt(25))
in order to put the whole thing into the sqrt, one must change the 3 into the sqrt 9
since ur mutiplying, u can put 1 * ((sqrt (25)) / (sqrt 9))
once u have ((sqrt (25)) / (sqrt 9)), u can take out the square root from each individual number, and give it to the whole thing
u will be left with 1*sqrt (25/9)
that gives u 5/3
which, equals our problem from the beginning: (1/3) (sqrt(25)) = (1/3) * 5 = 5/3
Whenever I multiply fractions, I multiply top to top, bottom to bottom. In step 2 they convert a denominator into a value that can be inputted into the square root. What's going on there?
if they didnt convert it, they wouldnt be able to input it into the sqrt
or u could also think abt it like this
gotcha
i don't think i know how to simply that either
lets see if I can use microsoft math for this
that's a big help, thank you
no probs man
except what i did isnt the answer for the problem u saw in the video thing
its the sqrt of the final thing i got
but thats alrdy on the video thing so
since all of it is under a sqaure root, would it be 2 root -1/x^3?
nah u cant separate it because its bonded by a "-" sign
if it was a multiplication, then u could bring out the 2
but with addition or subtraction, u cant
not without a bit of extra work you aren't
as-is, you lose a whole bunch of solutions
yes
if this is a solve question, you shouldn't divide by stuff that could be 0
instead consider factorisation
cosx = 2sinxcosx
i'm having trouble solving $\cot(2\pi t)=-1$
acex:
uhhh
Uhh
<@&268886789983436800> hi
Dang you sniped me
forgot i can delete stuff
Lmao
(for the mods seeing this, a guy posted an innapropiate pic and now it's deleted)
yea i banned em
Can someone explain to me why this is true?
take a look at $sin^2x - 6sinx + 9$
chene12:
what do you notice about the form of that expression
its ax^2+bx+c
yes it is quadratic, therefore try factoring
since the right side is all in terms of cscx, then use your reciprocal identities to set the left side in terms of cscx
ok now i got (1-3)/cscx but where does the top cscx come from?
ok good so $\frac{1}{cscx} - 3$
chene12:
np
Hello
Hi can someone check if my answer is correct? I got N 58.77 degrees E.
seems you got the direction wrong
Would it be S W?

