#help-27
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so it might be easier if we pretend like the negative isnt there for now
and then just apply it at the end
Ok
heres another way to write it that might make it simpler for you
-(x^8 d/dx (cosx) + (d/dx x^8) cosx)
thats what you need to do to solve this problem
can you use the bot to type it
im new here and unfamiliar with the bot but ill write it out on paper
understandable?
._.
okay basically what im saying is
take the derivative of cosx and x^8
then multiply the derivative of cosx by x^8, this is one term
and multiply the derivative of x^8 by cosx, this is the other term
the two terms are added to eachother and then we apply the negative sign from earlier
also im sorry but i gotta leave for a class
maybe you can ping a new helper since im struggling to explain it anyways
hmm
<@&286206848099549185>
I'm still having issues understanding how to solve this problem
go ahead
You have to use product rule
no clue
TooManyCooks
yea
So what does that mean if you want the derivative
separate them?
you already did that
but there's a rule to use when you have two things multiplied together
you used it repeatedly earlier
allo?
yes
that's exactly it
you separated them into x^8 and cos x
now i want you to use the product rule to give me an answer
you already told me the ingredients
you just need to put them together
if it helps, start by telling me what the product rule is
it’s fxg = f’•g+g’•f
(fg)', but yes that's it
So now I want you to use that to calculate the derivative
let's say f is x^8
and g is cos x
you don't have to give me the final answer. just tell me step-by-step what your solution is
close! but good progress
you missed a minus sign on the second term
remember (cos x)' = -sin x
Got it?
yes
Ok
Now, there's an overall minus sign in your problem
Remember, it was $-x^8 \cos x$
yea
TooManyCooks
yes
so you just bring that back by multiplying everything by minus sign
So with that, what's your final answer?
??
how?
you have a -1 multiplying your entire expression
that's the minus sign in front
I'm asking you to distribute it in your answer
$-\left( 8 x^7 \cos x - x^8 \sin x \right)$
TooManyCooks
oh ok
that's what you have right?
hm
or no?
Yea
You sure?
Yea
you have 2 minus signs on the second term
they should multiply each other
you're missing that
oh
first term is correct
lol no
_>
Ok now you need to distribute the minus sign
yes
yay
gj
what do you think
you had a similar problem before actually
and i seem to recall you did that correctly
so what do you think you should do here
When you see that you have to find a derivative of a fraction what do you think you should do?
cry
Not after we teach you
but
You’ll be laughing with joy
Because that’s what this company stands for
i love ur enthusiasm
Our pleasure
Have you heard of the quotient rule?
Got bored while doing calculus hw and made a song up about the quotient rule. Totally made up on the spot. https://www.facebook.com/navkarn
LYRICS:
we've got a problem here
a binomial in the denominator
and i need the derivative
low d high minus high d low
square the bottom and away we go
i'll use the quotient rule ...
Special Tha...
I’ve heard this helps people memorize it
Exactly
Closed by @native briar
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No
.reopen
✅
No ?
You need to distribute the 3x^2 to (x-1) to multiply the two
How?
When you bring x-1 to the numerator it has to be in parenthesis
So it’s 3x^2 times x - 3x^2 times 1
For the upper left parenthesis
f=√x+5 =x and f(a²)=aᵇ+c howwww
??
I’m confused
Bro this my math teacher killin my ass
what’s going on
how to find b-c
See this picture
I’m lost
Do you see where you put down (3x^2 * x-1)
Yep
It’s supposed to be (3x^2 * (x-1))
Minor difference but it changes the result, you have to distribute 3x^2
??
How would you find 3x^2 * (x-1)?
Ill help you give me a second
thx
The solution for this equation is zero
????
That’s close
Yea
So all of this over (x-1)^2?
So is the answer
2x^3-3x^2/(x-1)^2
<@&286206848099549185>
Oh what's up
Yes
Well you need parentheses in the numerator when you write fractions in text form
oYea sorry
i member that
wrong one
Here we go
I tried to separate the fraction by writing it as
5x^2/5x+20x/5x
Yeah now you can simplify it
that’s where I’m stuck
ok can you simplify 5x^2/5x as 5x?
or does it simplify to 5x^2?
@main gull
it simplifies as x
Because $\frac{5x^2}{5x}$ the gcf of the numerator and denominator is 5x
dldh06
is it bc 5x^2 simplifies to(5x*5x)
No
5x^2 = 5 * x * x
(5x * 5x) = (5x)^2
dldh06
Notice how the x's are common and can be canceled out
Yeah
..... I guess better late than never
Lmao I wanted to make sure the question was answered
What are you left when the x's get canceled out
20/5?
4/1?
And that equals?
4?
Yes
it simplifies to x+4?
Yes
but it is that the derivative?
No
the derivative is 1 right ?
Yes
Do you know how to derivate $\frac{1}{x^n}$?
WilmiRosa
No
WilmiRosa
do you know how to derivate $x^n$ ?
Almooost!
1/x^n = x^(-n)
yeah!
exactly
fr?
100%
so then would 8/x be 8x?
no?
what about the negative? :v
haha also, you write x/8 instead of 8/x jsjsj
ok so
I know that
9/x^5 can be written as 9x^-5
and so
can -8/x be written as -8x?
no, you lift the x to the numerator, so you have to change the sign of the exponent ^^
-8x^{-1}
ok, so you can express 9/x^5 - 8/x as... ?
the sign!!!!!
ah sorry
I wrote it down but forgot to type it
so then do I differentiate it
And then switch it back to get the answer ?
I got y’= -45x^-6+8x^-2
Thats peeerfect ^^
and that's your answer ^^
night!
yaw
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a
I do not understand how (x^2 -8)^2 -8 goes to the next step
where does the -16x^2 come from?
Do you know FOIL
yes
(a-b)^2 = ?
hmm
i dont understand
ohh wait i see
you foil it okay
(x^2-8)(x^2-8)
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need help with this one
If you reply plz tag me so I get a notification
@cerulean crater Has your question been resolved?
<@&286206848099549185>
Image of what I tried (a bit dark, sorry 😅 )
no one?
alright, it's getting late for me
.close
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unsure where to start and where to go, i have aguess but it isnt feasible
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help
am i doing this right
and what is the common ratio
<@&286206848099549185>
im sry im a bit stupid
i need help tho
so pls
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for 1.26, would a possible disadvantage be sampling bias because its only focusing on the eastern side of US?
or is this question looking for me to use the answers I obtained from 1.24 and 1.25 to come with a certain disadvantage?
@tranquil lantern Has your question been resolved?
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If i have a graph 0.5x²-1 do i graph this graph first by moving it by -1 on the y axis and then stretch it, or do i first stretch it by 0.5 and then move it on the y axis
Or are both ways correct?
Why don't you try both and see what happens
it is not the same.
check your order of operations and what they result in
Wdym
They re both the same
you start with x^2
Yes
you move it 1 down
you got x^2-1
Yes
you stretch it by .5
you got 0.5(x^2-1)
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@fringe bramble Has your question been resolved?
<@&286206848099549185>
I don't think this is planar
okay i figured
do you know to find subgraphs of k3,3 or k5?
unfortunately no
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is this question wrong worded?
A bit confusing i think. I'm not sure whether each was cut into 16 equal pieces or total 16 pieces as in each into 8 equal pieces.
ya right and ans is saying this
Ah. Lol. Badly worded then, yes.
ya i was confused what to do
thanks for telling
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Can you guys help me with this?
I need an example of the answers
What do you mean exactly? Examples of solutions to this inequality? Examples of solutions to similar problems?
I need help with a question
!help
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!help
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Solutions to that inequality
x=0, x=-42, x=0.5, and many many more
If you need examples, just graph it
,w graph y=(3x+1)/x+4 and y=1

Oh
,w graph y=(3x+1)/(x+4) and y=1 from x=-3 to x=2
It says that 3 of these given choices are the answers
,w graph graph y=(3x+1)/(x+4) and y=1 from x=-6 to x=-2
dang
Then let's go through it arithmetically rather than graphically
@bold cypress Do you have any idea where to start? Have you perhaps already tried something
I'll be right back
What did you try so far?
Stuck here so far
Hmmm okay, solving for the boundaries I see
That wasn't the method I had in mind but it's actually just as efficient so props for that
Are these correct?
Nothing tells you that all of these boundaries give valid solutions
In fact with your method right now every inequality would be true everywhere, I don't know if you even noticed that
These "boundaries" as I'm calling them just tell you where to check
Either all of the solutions in one of the intervals are valid or they're all wrong
@bold cypress For each of these intervals, pick a single value from it, and check it against your inequality
Idk man it just asks the intervals it disregards wether it is true or not
Im trippin balls
It doesn't care whether your interval is actually a solution to the inequality?
Why even bother then
So are these the intervals?
...I just answered that
The "boundaries" you found just tell you in which intervals you have to check
The points at which (3x+1)/(x+4)=1 tell you where it crosses the line y=1 and the points at which x+4=0 tell you all of the discontinuities
,w graph y=(3x+1)/(x+4)=1 and y=1 from x=-2 to x=2
Wolfram Alpha doesn't understand your query!
Perhaps try rephrasing your question?
Click here to refine your query online
??
Anyways, this
Where it crosses y=1, x goes from a valid solution to a non-valid solution
And where there is a discontinuity (where the denominator goes to 0), y jumps from -infinity to infinity
This is why those "boundaries" give you all the intervals to consider
Now you just need, for each interval, to pick one value from it
And whether that value is a solution tells you whether the whole interval is a valid solution
@bold cypress Does that make sense at all?
Hold on im tryna keep up
Yeah I was expecting that kind of response, I'll try to show it in a more intuitive way
whoops
It’s just that our teacher did not mention anything about graphing and boundaries. He just taught us how to find the solution set and intervals of a rational equation
He probably just taught you a different method
And wether it is true or not
By "true" and "valid" I just mean that it is a solution to the inequality
I'm going along with this whole "boundary" thing because it works quite well and because that's basically what you started doing
@bold cypress See how your "boundaries" divide the curve into 3 sections?
If you slowly change x, the only way for it to go from a solution to a non-solution or vice-versa is to go through the y=1 line or have a discontinuity
On the right, where you replaced your < with a =, you got a point where it crosses the y=1 line
Thank you for ur time man
This is why as x reaches 3/2 (3x+1)/(x+4) goes from being less than 1 to being greater than or equal to 1
And the point at which the denominator reaches 0 gives you a discontinuity as you can see on the graph
@bold cypress This is why, if you picture a point following along the curve's path, as it reaches x=-4, it will go from a non-solution to a solution, and why as it reaches x=3/2 it will go from a solution to a non-solution again
Points where the curve crosses y=1 and points of discontinuity are where non-solutions may become solutions or vice versa
And because there's none of that in the interval (-4,3/2), you know that if one of the x-values within this interval is a solution then all x-values within this interval are solutions
Let me say that again, since in the interval (-4,3/2) the function y=(3x+1)/(x+4) doesn't cross y=1 and doesn't have a discontinuous jump, there's no way that anywhere in there it goes from a solution to a non-solution or vice versa
So either they're all solutions or all non-solutions
@bold cypress You got all of that?
Ping me once you get back
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!show
Show your work, and if possible, explain where you are stuck.
I have no idea what to do
as per the graph, what is f(-7)?
Do you know what are constant functions?
5?
No
Check b
3 or 6
5
Yes
So the answer is 5 for first 2 questions?
Basically b=5 for the second bit
Cuz that's the y intercept
The first bit is constant at 5
The last bit is also constant
Gtg
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I haven't started doing this yet, I'm still pretty new to Calculus type math and are only going to the take the basic math course.
I was wondering if any of you have some tips, on some videos/problems to solve before tackling this problem? I don't understand how to solve this and would like to practice and understand first
@elfin grotto Has your question been resolved?
This calculus video tutorial provides a basic introduction into u-substitution. It explains how to integrate using u-substitution. You need to determine which part of the function to set equal to the u variable and you to find the derivative of u to get du and solve for dx. After replacing all x variables with u variables, find the antideriva...
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hi i kinda dont get it where i made mistake, help. at the first picture is where i do exercise and second of the right result
Last term also 2y⁴x
Its 12y⁴x
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Hi everyone, I'm really struggling with an exercise in the middle of Armstrong, showing that if maps $f,g:S^{n-1}\to X$ are homotopic via $F$, then $X\cup_f S^{n-1}$ is homotopic to $X\cup_g S^{n-1}.$ \
The strategy online seems to be to see both are deformation retractions of the larger attachment space: $X\cup_F (D^n \times I)$.
(For example, a sketch here does it that way: https://math.stackexchange.com/questions/608908/ ) \
In the sketch one first constructs deformation retraction $d_f$ from $D^n \times I$ down to a space $D^n\times {0}$, along which $F$ looks just like $f$ (and similarly a deformation retraction $d_g$ to $D^n\times {1}$, where $F$ looks like $g$). \
Somehow this $d_f$ yields a deformation retraction on the attachment-spaces themselves: $(X \cup_F (D^n\times I))$ goes down to $(X\cup_f (D^n\times {0}))$. \
My question: how is this new deformation retraction on the attatchment spaces defined from $d_f$?
enthdegree
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how to do part c
this is what I did:
Dx/dt = answer of part a
solved differential equaton, got x in terms of t. then i substituted part b to solve for x
but i ended up getting 0
@mighty copper Has your question been resolved?
for c part too?
for c, we need x
yeaa i needed help with c
ah ok
i did dx/dt = the expression I got in a. solved the differential and substituted t from part b
do we have the same here?
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also, assuming i did it correctly
at the end of the integration to get x(t), dont sub your u back in
instead try to rewrite the u(t) with the t you got from part b)
that makes it nicer
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4x^4-4x^2+4x-1 =0
are you trying to solve?
yeah for x
have you tried to factorise?
have you been given any info?
that i have to do scomposition of first member and then use product cancellation law
so my first thought is, what does it look similar to?
a quadratic equation?
yess
now, if it didnt have that fourth term
if one of the terms was gone
could you create a quadratic - type factorisation
ahh should i try but subtracting both sides by a negative member?
hm, maybe not
so
lets say you only took 3 of the values
is it possible to create a quadratic of some sort
something of form
(a+b) * (a-b)
yes
or (a+b) * (a+b)
i did try that
i basically tried every possible thing like ruffini, binomial difference and playing with different members
okay 1 sec
ill try and work you through what my approach what
was*
so, take (a+b) (a+b) or (a+b)(a-b)
we have a constant, and also an x^4 value
these can only be obtained through two of the same type, right?\
yes
would we use (a+b) (a+b) or (a+b)(a-b), and are we using +b on both, or -b on one
i can proceed with (2x^2)^2+ 2^)
i would say, forget the rest of the equation
to get x^4
or 1
what will A and B be?
2x^2+1 2x^2-1
perfect start
and it will be +1, -1, since the final term is a negative
so if we expand that, what terms do we have?
4x^4-1?
great
so we are a little closer
now, what other terms could we add to the bracket
that doesnt create a larger power than x^4, or smaller than x^0 (or 1)
i'm thinking
we have (x^2, x^0)
........Numan. 😑
yes??
(Seinfeld reference. Carry on)
hhahahah
hahahaah
these are the powers of the terms we have in the brackets currently, what else could we play with
signs?? maybe
to try and create the remaining terms of the equation (x^2, and x^1)
maybe
(x^2, x^0, and we can add x^1)?
i've been working on this one for 3 hours so my brain is kind of fried rn
sso, just x
its okay ahahha
like
we could do something like
(2x^2 + ax + 1) * (2x^2 +bx - 1)
since ax * bx = c * x^2
okk
and ax or bx * 1 = cx?
do you get that?
now, we can either expand the general form of the brackets
nope
yes
the x^1 term is gotten by multiplying mixed powers right?
yess
ahhh ok
now i get it
4x^4-4x^2+4x-1=0
thats why we can determine some guaranteed terms
you can only get the highest term by multiplying two things together, right?
yess
and the lowest by multiplying two, but the ones in between have multiple elements
now
i know that there must be a way to get 4x
and if we use x^2 and constants, can we get 4x?
are there any possible combinations?
at all?
i would suggest no, can you see why?
ur right
to get 4x
we must use some combination of x and constants
so
thats why
we have (2x^2 + ax + 1) (2x^2 +bx - 1)
ok
we already know we must have 2x^2 and 1 since they are used to obtain 4x^4 and -1
then ax and bx must somehow reach 4x and -4x^2
now, uve almost worked it out i can see already, but what is the highest term that ax * bx can achieve?
ax 4x^2 and bx 4x
honestly i didnt understand the qs
okay thats alright
ill try and explain
so we want ax*bx to hit the -4x^2 term
since (2x^2 +1) (2x^2 -1) = 4x^4-1
the only way to create -4x^2 is by multiplying some x terms
and i can guess
-2x and 2x
u actually found
yes
earlier u were very closer
maybe
so actually
u can just say
since the only way to create -4x^2 is with 2x and -2x
you can just say
(2x^2 +2x -1) * (2x^2 -2x + 1)
is the solution
its like adding and subtracting nonesistent variables and breaking the existing ones
yes u can say that
i dont know which term is used in english to describe this method
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What is the differenece between the formula for combinations and permutations?
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Can someone explain what he did from step 2 to step 3? I'm feeling very stupid right now. I understand it up to step 2, but i don't understand what he did to get from step 2 to 3
just factored out (n+1)/6 from both fractions
the left fraction is (n+1)/6 times n(2n+1), and the right one is (n+1)/6 times 6(n+1)
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Hi
Can anyone help me with this problem
An ellipse with its foci on the y-axis and passing through the focus of a parabola (4,0) , the ellipse pass through the Directrix of the Parabola (y²=8X) A segment with length 10 √3 Find the equation of the ellipse
The only thing i came up with was B = 4
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can you scan the paper? it is not very readable
I dont know how to scan using discord. Is this better?
not really, try using an app called "CamScanner"
This is it right?
what topic is this?
Trig
Using the compound angle formulae Rcos(x+a) and Rsin(x+a)
Is the name of the sheet
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whats the transformation for the 3 inside the root sqaure
note that sqrt(3x) = sqrt(3) * sqrt(x)
okay so what would the tranformation be?
,tex .transformation rules
ℝam()n()v
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can sigma notation like this be solve with integrals?
i was taught sigma notation is like a "rough sum" and integral is a "smooth sum" (includes non-integers) but integrals are kinda easier to work with so curious if they can solve sigma notation problems
you can certainly express it as an integral (of a step function, for example), but if you want to compute the actual value of the sum, i don't think using an integral is going to help you
is there a faster way to calculate sums than manually adding it?
some types of sums, yes
you can use facts like $\sum_{n=1}^{N} n = \frac{N(N+1)}{2}$ for example
Bungo
could apply distribution and association
in this case you're only summing four numbers, so it may well be faster just to brute force it rather than expressing it in terms of simpler sums
for this one I did:
(2*2 - 1) + (2 * 3 - 1) + (2 * 4 - 1) + (2 * 5 - 1)
if it went from 2 to 1,000,000, or some arbitary large number, how would I do a problem like that?
something like this:
$$\sum_{j=2}^{1000000}(2j - 1) = 2\sum_{j=2}^{1000000}j - \sum_{j=2}^{1000000}1$$
Bungo
ohh
on the right hand side, for the first sum you can use
$$\sum_{j=2}^{N} j = \sum_{j=1}^{N} j - 1$$
and use the formula I wrote above
Bungo
i got 1,000,001,000,002
i mighta messed up somewhere'
oh its actually a pretty number
hmm, let's see, 2(N)(N+1)/2 - 2 - 999999 = 999999999999
yep checks out
N = 1000000 in that formula
ah yeah I made a couple mistakes, I think I added 1,000,000 and I changed N + 1 in the formula to N + 2 because I thought maybe + 1 was the lower limit of your sum
the -2 in my calculation is the adjustment due to starting the sum at j=2 instead of j=1
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anyone could help me with this?
Can you put into simpler words, what makes a set "good"?
By "good" you mean well ordered set?
no
its just like
a name of a set
it could also be "bad"
it doesnt matter it just has to fit the statement following
conditions
i guess that every x value in the set has atleast one a value thats smaller than x
@humble flare well said!
[1,2) isn't good, because there's nothing smaller than 1 in the set.
true
Any change we could make to it?
Can't be a finite set
Note that [1,2) is a real interval
So 1.5 is in there
Oh wait whoops I am the one who misread
so maybe make it A= Z
Yes okay I see what you're saying now. Yes that works
To just have a set of integers that trails off to negative infinity
I was personally thinking of the real set (1,2)
1 isn't in the set
why
Nvm, let's just go with your suggestion.
So you should use {} and not () for a set
So you want {1,0,-1,-2...}
Also Z is another example, that does work too
yeah
i think A=Z is easiest
so i guess
start with WTS
every x part of A, there exists atleast one a whcih is part of A such that a < x
but after that idk
would proof by induction work for this?
hello?
If you pick n, then n-1 is smaller
what would be the base case?
Actually that's not even induction. Just a direct proof
yea
so i could prove it without induction
is saying take a to be x-1
then a will always be smaller than x
Yeah that works!
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How do i find secx in terms of t?
so sec x can be wriiten as (1/2)(t + 1/t)
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Was watching my professors video
and was wondering how she was able to figure out what type of discontinuity based on the function
can someone please help me understand how come the answer is removable discontinuty just based off hte function
If limit at the point exists then it is removable discontinuity
If limit dne then it is non removable
plug k into x2 and when k-1+ to the equation put it to the other side and see if the equation is still discontinous or not
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need help
7 is one right?
what makes it a 0?
what's "it"
what makes certain x points a 0
wdym?
so
is 0 and 2 a 0 too or?
you mean f'(0) and f'(2)?
yes
yea those points also have derivative of 0
derivative is like the slope of a line at one point
f'(3) and f'(5) would not be a zero correct?
f'3 and f'(5) dont have derivatives it kinda complicated but they are not 0
no
think of f'(number) as the slope of that point
at f'(9)
the graph line is going down
so its slope is negative and not 0
it is only 0 when the line is not moving up or down
ok so f'(8) is also not a zero
yeah
you know how limit calculate for one point
yeah i think so
well
you can just go to one point
and draw a line paralell to it
and approximate the slope of that line
its kinda what derivative is
i will send image
I feel like I already have all the zeros though
yea i think those right
yeah
you draw a flat line and its slope aligns
like a tangent line
yea it is a tangent line
how would you do it for f'(3) tho