#help-26
1 messages · Page 27 of 1
but putting x = 3 satisfies my eqn and its real 
Yeah i know
If your domain was negative real numbers and range was positive integers and you have an injection, this would be a valid function
Wellt echnically its still a valid function
Also ypur calculator might just be coded to only consider positive values for the base so it took a shortcut
not my pic lol
so your saying 3 should be "one" of the answers?
solutions*
wodefok
Often considered the principal solution
ok hpld on lets ask wolfram alpha
,w log_{-2}{-8}
Heh
I guess it isnt the principal solution
the fuck
Lemme just boil it down to this: negative logs get weird and often involve complex numbers
ye
Its not wrong
Ok yeah lemme explain
i dont even see a 3 in there
and you say its (my method) not wrong
im probably the wrongest ive ever been
Youre not
3 is just not the principal solution
Do you want to know how they got this?
How familiar are you with log properties
ik
ok, so wolfram alpha calls "ln" "log"
is this prob the combined eqn of all the solutions?
The comboned equation would be $$\frac{log(8)+ni\pi}{log(2)+mi\pi}$$
GarlicB
Ayy first try
Actually i lied
n and m have to be odd integers
But if you take n=3 and m=1, you get 3
Or really any n=3m, for all m odd
man.
Ok wait
3 is an answer
Yes
This is important
i meant no as an answer lol
Technically it is if you define the right domain and range
If you pick* the right domain and range
i've never done that
- plus that aint gonnna come in my exam too
its just gonna fuck my brain 😭
Well log_{-2}(-8) should be coming on your exams either but thats just my opinion
idk my teacher never thought it plus never saw it in pyqs
So if you want the simple answer, 3 is technically correct
If you want a more complicated answer, let me know
Otherwise feelf ree to close
Im assuming your teacher only wants the real answer
a
my teacher didnt ask that
its just a diff guys que and i thought he raised a good doubt
and i thought yes 3 should be an answer
and you said it is
so im correct
So i woul say "yes, but..."
i just thought smth must be wrong in my solving
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Lol np
Feel free to ask me if you want the full explnanation
I kinda sprung it onto you when you didnt want it
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All endomorphisms of a field are automorphisms
?
help
Since every homomorphism of a field is injective
Then all endomorphisms of a field are injective
injective doesnt imply surjective?
you might need choice, but u can have non automorphisms afaik
maybe thats bs
i misremembered, seems ur right
wait no comments/answer say otherwise
yh good idea to try think of examples before seeing
they arent too hard
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I'm not sure how v_i which is 18.975 changed into v_i1 which is 12.65
v_i1 and v_f should be the same?
,calc (30 - (0.5)(9.8)(2.25))/(1.5)
?
Result:
12.65
who's 18.975?
what they did was calculate the velocity when you saw the melon
which is 12.65
then taking that as final velocity for the motion before you saw the melon and 0 to be intitial (dropped), they get the top small height
and sum the heights
Then is the answer 17.58 correct?
email: thephysicisttutor@gmail.com
A watermelon is dropped from the edge of the roof of a building and falls to the ground. You are standing on the sidewalk and see the watermelon falling when it is 30.0 m above the ground. Then 1.50 s after you first spot it, the watermelon lands at your feet. What is the height of the building? Neglect air res...
This is an embedded link with timestamp
If you wanna take a look
Result:
18.975
?
like really messed up
What is?
I got my height for the second one 17.58
Used g = 10
Not sure if you can see my work process
i can
So the total height is d + 30m
yeah nothing wrong
,calc (30 - 11.25)/(1.5)
Result:
12.5
you shouldnt get 18.75
Why?
you forgot to divide by 1.5
Oh
That makes sense
Hold up
Oh
I get 7.8 m for the second height
That's much similar ig
Ohhh

That parentheses were multiplication
I thought it was some kind of parameter
2:44 am moment
Thanks though
Love ya
.close
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isn't this wrong?
i think i^100 should be -1
sqrt(-1) to the power of 2 aka squared should be -1
Dyssrupt
Imaginary numbers after the 4th power are constantly repeating
Dyssrupt
oh wait
i thought i^2 was equal to i^50
i just made a stupid assumption
nvm guys lol
thanks for correcting me
.close
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wow
it got me again
in the second example lol
i made the assumption that i^51 would be just i because
i^100 is even
and i^100 is 1
so i just multiplied by i
but that assumption turned out to be wrong
i exponent property is very trappy
heh
if you remeber the value of i i2 i3 i4
you probably wont have much prob with theses type of ques
Dyssrupt
If you know what an argand diagram is the power it rotates it 90 degrees
just dividing the power by 4 and looking at the remainder will be the power of i
discord's lagging
im bad at typing ngl
i^0 is “1, 0” as in (1 + 0i)
i^1 is “0, 1” as in (0 + 1i)
i^2 is “-1, 0” as in (-1 + 0i)
i^3 is “0, -1” as in (0 + (-1)i)
Then it repeats
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$P(r+s,n) = \sum_{k = 0}^{n} \binom{n}{k} P(r,k)P(s,n-k)$
Ziggy
$\frac{(r+s)!}{(n-r-s)!} = \sum_{k=0}^n \left(\frac{n!}{k!(n-k)!}\right) \left(\frac{r!}{(r-k)!}\right)\left(\frac{s!}{(s-n+k)!}\right)$
Ziggy
$\frac{(r+s)!}{(n-r-s)!} = 2^n \left(\frac{r!}{(r-k)!}\right)\left(\frac{s!}{(s-n+k)!}\right)$
Ziggy
can i do that?
What is k in that expression?
Ziggy
Ye sorry
the size of the subset
But what I wanted to say is that $\Big(\dfrac{n!}{k!(n-k)!}\Big)\neq 2^n$
Joseph.P
yes but the sum does
Oh thought all the expression was in the sum
No you can’t actually because if so you would have $$(a+b)^n=\sum_{k=0}^n\binom{n}{k}a^kb^{n-k}=2^na^kb^{n-k}$$ and in the last expression you don’t even know what is $k$.
Joseph.P
This expression is wrong
okay
this one isnt though
$P(r+s,n) = \sum_{k = 0}^{n} \binom{n}{k} P(r,k)P(s,n-k)$
Ziggy
First what’s P ?
You sure it’s not arrangements ? Because if it’s not you got the wrong formula
$(x+y)^n = \sum_{k = 0}^{n} \binom{n}{k} x^ky^{k-n}$
Ziggy
what i've written is correct
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hi so ive made some progress
this is what ive done so far but i am getting a wrong answer
maybe it should be y(t) = (t^3+1) (e^(t^2))
?
this seems like a good shout
your working seems fine to me
lol i have one more attempt left
alright ima take a shot
LETS GO BABY
thanks a lot for your help yesterday too man
luv u. have a good wknd
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How to find pyahtogeream therom
for iscoelse triangle
could you be more specific, do you have a picture of a question you want this for?
the pythagorean theorem applies to right angle triangles
this isosceles triangle can be split into two right angle triangles (see the dotted line)
the only info youre missing is the base length of one of those two right angle triangles, what would that be?
thats the base length of the isosceles
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thanks
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Learning some real analysis, I want to check a proof I did that $a_n=n^3$ for $n\in\mathbb{N}$ is unbounded from above, so we are working towards the statement $\forall C\in\mathbb{R},\exists n\in\mathbb{N}, a_n>C$
bostock
so for all $C\in\mathbb{R}$, there exists $n$ such that $n^3=n\cdot n^2>C$ which is true as $n\in\mathbb{N}$ and $n^2, C\in\mathbb{R}$ so the Archimedean property applies
bostock
Therefore the statement we are working towards is true so $n^3$ is unbounded from above
bostock
<@&286206848099549185>
@pseudo locust Has your question been resolved?
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how would i do b? i tried by parts, and got stuck at integrating sec^3 theta, thanks
,rotate
Trig sub,
x = sec(t)
yes i did that
You'll get part a back
OH sorry I thought part b was the other one
more integration by parts ig
sec^2x and sec x
I wouldn't start that way. Start with a trig sub x = 2sec(t)
ye im trying this rn
do i by parts tan^2t*sect?
yes
Turn it into sin and cos
No wait, that won't be it
tan^2=sec^2-1
wait im getting a bit closer
update pic pls
which step?
at tan^2*sec right
ohh
yep i wrote 4integrate(sec^2u-1)secu du
Integral of tan²(t) is not tan(t) - t
Huh, I stand corrected
Consider the tan^2x as sec^2x-1 and integrate that
Smart
so anyways now im stuck at integrate sec^3u - secu du
sec³ is dreaded and I was hoping we didn't have to go there
yeah
then turn the tan^2 into (sec^2u-1)
yeah
Here's a clever way
https://math.stackexchange.com/questions/179935/how-to-integrate-sec3-x-dx
uhh
yo waittt
what
i am getting something here hold on
so what's the integral again
integrate sqrt(x^2-4)
wait im rewriting everything to make it clear
kk
!status
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6. None of the above
nice
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Make the slope perpendicular?
yes
if it's perpendicular, then the it's the negative reciprocal of the original slope
You know the slope of the perpendicular line but that line passes through (-1, -8)
So the equation of a line is y = mx + b. You know m
You use that point to find b
Y=10x+2
Yeah that's right
Ok thanks!
Also i got this one. Ik i gotta isolate x
By dividing y
Dividing x
Yeah idk bro
how would you solve for $x$ if you were given something like
$$5 = 7x - 9$$
ℝam()n()v
by?
same idea applies here
First wouldn’t I have to move y to the other side and remove the x
same idea applies here
the equation is in the exact same form, except i replaced y,6m,2b with numerical values
the process for isolating x is exactly the same
separate terms with x from terms without
divide by coefficient of x
So i subtract y with 2b
Uhh
I added
added what exactly
and apply the exact same idea to what you have here
So add -2b
Yup
you did not
yes
So i add just 2b
ℝam()n()v
and recall what you did when you had
$$14 = 7x$$
ℝam()n()v
Divide 6m both sides ?
yes
Y+2b/6m=x
() are needed
to clearly indicate numerators and denominators
and they will be necessary for the system to interpret the desired result
(y + 2b)/(6m) = x
oh, if the system allows you to input fractions like that then those () aren't needed then
they would be for single line text input
But its fine if they are kept right
yes
no
y_1 and y_2 are lines
no
Ah ok
the vertical coordinate of the intersection isn't even 0
(3,0) would refer to that green point
Ohh
And this one I’m not sure how this pulled together into a slope intercept form
you are essentially given two points
use a method of determining a straight line equation using two points
like two-point formula
or first determining the slope then applying point slope formula
(which is pretty much the same thing)
I got like y=5/6x+.33
To get b value u choose one of the ordered pairs right
So I’d have to put 4 in for x
So 5/4 x 4
firstly, those indexes should be subscripts not superscripts
$$x_1,y_1,x_2,y_2$$
NOT
$$x^1,x^2,y^1,y^2$$
secondly you've misidentified their values
ℝam()n()v
f(3) = 4
indicates that when x=3, y=4
for the slope, yes
where's
-6/5(-2)=2.4
coming from
F(-2)=-2
To find b?
how's that supposed to help find b
Add a value to x
that just looks like you're multiplying slope to an x coord
What else would u do
show full equations to clearly show what's going on
so you don't misplace values, screw up signs / other operations
if you want to find b that way, start with something like
y = mx + b
do the substitution and do clear manipulation to get b
^
So y = 6/5x + .4
ideally you should write the 0 before the .
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its the first
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The question is : determine whether f and g r inverse functions
,rotate
are you doing d?
Yes
so, what's wrong?
And I want to make sure if I answered correctly
you did
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6
Σ (1/n+1)
n=1
help me solve this please
telescoping?
wait a sec
$\sum_{n=1}^6 \frac{1-n+n}{n+1} = \sum_{n=1}^6 \left(1 - \frac{n}{n+1} \right)$
Herels
hmm it wont work i guess
squaring what
HOW DOES IT WORKK?
oops my bad i wasntt T-T sorryy
so its 1?
no, do you know how to manipulate fractions ?
$\frac{1+n-n}{n+1} = \frac{n+1-n}{n+1} = \frac{n+1}{n+1} - \frac{n}{n+1} = 1-\frac{n}{n+1}$
Herels
wdym
what does harmonic progression even mean
ln(n+1) + γ + O(n)
I believe
well
Its just a sum
$\sum_{k=1}^n \frac{1}{k}$ is the harmonic progression
Herels
its just a variable... nothing deep
so the answer is 1-n/n+1 ??
Ive never said that...
Basically, your sum is not possible to calculate with regular ways
And we said your sum is like the harmonic progression
$\sum_{k=1}^n \frac{1}{k} = \ln(n) + γ + O(1)$
Herels
OMG WHAT R THOSE SYMBOLS
let ignore that
anyway, your sum is not possible to calculate
with regular ways
Me neither
thats why we talked about the harmonic progression
,w \sum_{n=1}^6 \frac{1}{n+1}
at least wolfram alpha gaves the result
yes
omg im finally doing smthing rifght for the 1st time in a while
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anyone help with this ? just answers is enough
we don't give out answers.
oh ok my bad
!status
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2. I have begun but got stuck midway
3. I got an answer but I'm told it's wrong
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6. None of the above
do you know basic algebra
yes
ok
sorta
let x be the amount of money invested at 4%
can you tell me an expression for how much money was invested at 7%?
both in dollars obviously.
you can do it with one
oh ok
since you know how much was invested in total
(76000)
phyllis has 76000 dollars of which he invests x into a 4% account, and the rest into a 7% account.
how much did he invest into the 7% account?
76000-x
76000 times 4% ?
yes, so how much interest did that give him
you don't need to know either one
it's a 1 year deposit
it makes no difference at all lmao
is it x times 4%
ooh ok
and how much did he earn from the 7% investment?
(76000-x) times 7%
0.07(76000-x)
ok
so now can you write the equation that says the guy's total earnings are 4240?
yes but write it out
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is this euclidean algorithm correct i think its wrong at the step 2=(1)(2)+0 please verify
should it be a=a.1+0 instead
<@&286206848099549185>
?
shouldnt every reminder go down 3 times
what
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Hi can I have help with this math problem. I have gotten the answer 2/4
Hi can I have help with this math problem. I have gotten the answer 2/4
and can I have a explanation
First of all, don't you think 9 should be included in the range?
Since there is a point on the graph with y-coord equal to 9
I.e., (1, 9)
Yes, but you put ) instead of ] next to the 9 in your answer
The domain that you have given is correct, yes
okay
Another issue with your answer for the range is that you are including some negative numbers in it
It would mean the graph somewhere goes below the y-axis
oh
That, as you can see, does not happen
yes
It's always above the y-axis except when the graph intersects it
okay
So you instead have [0, 9] as the range
and 0 not 1
oh okay
Oh and that too yeah
what is the definition of the amplitude?
to be honest i am not 100 percent sure
look it up then in your notes
it is the the amount by which the graph of the function travels above and below its midline.
i dont know how to find the midline or what it is
mid line
middle \
well, its what you think it is 😄
okay
2?
yeah
and what is the definition of period?
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Let $z\in\overline{\mathbb{Z}}$ an algebraic integer of conjugates $z_1,...,z_n$. Let $P\in\mathbb{Q}[X]$ also be a polynomial of degree at most $n−1$, and $p\in\mathbb{N}$ a prime number. Which of the following statements are always true?
All $P(z_1),...,P(z_n)$ are conjugates of $P(z)$. \
The conjugates of $P(z)$ are among $P(z_1),...,P(z_n)$. \
If $P(z)$ is an algebraic integer, then $P\in\mathbb{Z}[X]$ \
The sequence $z,z^2,z^3,...$ of the powers of z contains at least one term worth 0 or 1 modulo p. \
$\overline{\mathbb{Z}}$ modulo $p$, i.e. $\overline{\mathbb{Z}}/p\overline{\mathbb{Z }}$ is a body. \
There are an infinity of algebraic integers two to two distinct modulo p.
Joseph.P
I think the third one and the fourth are wrong
@supple sun Has your question been resolved?
#groups-rings-fields might be a better place to ask
but also, instead of body, do you mean "field"?
is this translated from german/french?
Translated from the french
In French it’s "corps" so maybe
Thanks
Do I close this channel ?
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.close
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How do I solve this
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am i correct?
Where did 2 come from in b
ty tho 😭💖
(c) should be 7
7.0
Yeah
Do you know the basic limit laws?
just substitute all the values
@stuck bronze Has your question been resolved?
oui
but
for question e
do you think my answer will get accepted if I write DNE
or should I write D.N.E
I have no idea fr
oop-
nvm
.close
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helllo everyone E_1 and every E_alpha are subspaces of E
i dont understand the $\pi_{\alpha}\circ i_\beta$ part
calculus is fun
@vital moth Has your question been resolved?
<@&286206848099549185>
Write every x as sum(x_gamma) if you need a third index
If x is in E_alpha, then you can write x = x_alpha
are you talking about the piecewise map pi_alpha circ i_beta
So first of all, if alpha=beta, then $\pi_{\alpha}\circ i_\beta(x) = \pi_{\alpha}\circ i_\alpha(x_\alpha) = \pi_\alpha(x_\alpha) = x_\alpha = x$
rafilou2003
If $\alpha \neq \beta$, then $\pi_{\alpha}\circ i_\beta(x) = \pi_{\alpha}\circ i_\beta(x_\beta) = \pi_\alpha(x_\beta) = 0$
rafilou2003
This is because x is in E_alpha so we can write x = x_alpha
And this is because x is in E_beta so we can write x = x_beta so the coefficient in x_alpha is null
isnt it i the output of the function at beta=alpha?
i didnt understand what was the letter written
"i" is for identity here
oh ok
So here alpha=beta, then $\pi_{\alpha}\circ i_\beta(x) = x = i(x)$
rafilou2003
So we can write in this case the equality between linear maps $\pi_{\alpha}\circ i_\beta = \iota$
yea sure
I prefer the notation Id tho
rafilou2003
Oh yeah it's a iota
but how is $\pi_{\alpha}\circ x_{\beta}=0$?
calculus is fun
When alpha neq beta
for alpha neq beta
yea i wanted to continue the question
Ok
So for $x \in E_\beta$, as mentionned, we can write $x = \sum_{\alpha}x_\alpha = x_\beta$
rafilou2003
is it bc $x_{\beta} \notin E_{\alpha}$?
calculus is fun
Nono, it's because E_alpha and E_beta are in direct sum
So if x is in E_beta, its projection in E_alpha is 0
how do you know that they are
I can read "direct sum of subspaces"
oh it says $E=\sum_{\alpha}{E_{\alpha}}$ is a direct sum of subspaces
calculus is fun
Yep
So E_alpha and E_beta are in direct sum
So for any vector of E_beta, its projection on E_alpha is the 0 vector
so for $\beta \neq \alpha$ we have $E_{\alpha}\cap E_{\beta}=0$
calculus is fun
so if x_beta is in E_alpha then it must be 0 otherwise it isnt in E_alpha and its projection will also be 0?
Yes
why do we consider it 0 if x_beta notin E_alpha
We dont consider it, it is
why dont we say that pi_alpha circ x_beta doesnt exist
Because it does exist and is 0
why is it 0
Since E_alpha and E_beta are in direct sum, any element x of E_beta can be written IN A UNIQUE WAY AS x = x_alpha + x_beta + ...
(Where x_alpha in E_alpha, etc...)
Since we also can write x = 0 + x + ...
Then this IS the unique way and its coefficient x_alpha = 0
do you mean x_beta
forgive me if i am being stupid but i am heading to bed after this and you can say i am starting to get into bot mode
If x is in E_beta, then x_beta = x and x_alpha = 0
Because x = x_alpha + x_beta + ... = 0 + x + ...
yea i got what you mean
by coef in x_alpha
the term ax_alpha in the sum that represents x_beta is just 0
Exactly
so its projection onto E_alpha is 0
Yep
tysm for your time i showed maximum stupidity in this and the other channel about continuity
Nah its alr
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I don't understand how this fits
this is a 3x4 matrix
how can there be a vector x_4 with 4 entries?
how is that?
Remember that an (m×n) matrix and a (k×l) matrix can only be multiplied if n =k, and will then output an (m×l) matrix
The number of columns of the first matrix has to be equal to the number of rows of the second
How many columns does an (m×n) matrix have?
n
Yes
why would the columns and rows switch places
I suggest looking at how matrix multiplication works again
again implies I ran into it
which I have not
oh the next 3blue1brown video says matrix multiplication
Where does this come from? Because if you haven't seen matrix multiplication I don’t think a teacher would let you do those kinds of exercises on your own
my homework?
Or at least have you seen how multiplying a matrix with a vector works?
So, how are you supposed to do this exercise if you can't compute Ax ?
Ok, so can you explain how does that work?
row entries of a vertical vector X are paired with the columns of a matrix A
for whatever reason
Yes
Basically, from an existing vector x, we create a new vector, Ax, by taking the weighted sum of its coefficients
The "weights" are given by the matrix A
how can you call a matrix bigger than 1 row by x columns or 1 column by x rows a vector?
Idk if that is your question, but a vector here is just an element of R^n, but n can be different
x can be a vector of R⁴ while Ax can be a vector of R³
does R^n describe a vector space?
that is difficult to comprehend
does that mean a vector can be literally anything?
like a collection of vectors?
A vector, in general, is an element of a vector space
what do you mean by element?
Ie anything that is inside a vector space
For example, (1,2,4) is an element of R³
We write $(1,2,4)\in \bR^3$
rafilou2003
R³ is a vector space, so by definition, (1,2,4) is a vector
is a 2x3 matrix a vector in R^3?
No, but it's a vector in $M_{2,3}(\bR)$
rafilou2003
woah wtf is that
The set of 2×3 matrices
okay, so you weren't calling a matrix a vector
I was just forgetting how vector multiplication worked
my b
Here I was trying to keep "vector" specifically for objects in R^n
@soft lily Has your question been resolved?
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I need help with this I'm doing part a right now
I can't help you because I'm heading out but just as a word of advice, don't use ChatGPT to do math. It's often inaccurate or wrong (for the time being)
Do you know how to find k?
This is the correct formula
Because chat gpt gave me 2 different formulas one with e and one with a
You've already used the starting price (in 2010) as information. There's still one piece of information you haven't used
Wait I'm sorry could you please define what p0 and e and k mean I want to write them down
And t
I just forgot a lot of this stuff
Is it the 7 years
P0 is the starting price
e is just short for exponential function
So P(t) = P0 exp(kt)
Finally, k is called the growth factor
And yes you haven't used this yet
But just in general tho
The starting value
Thank you
At t=0
Ok thank you
Wait so what does e do?
e is for the "natural exponentiation"
because the derivative of f(t) = e^t remains e^t
and so we write e = exp(1)
yes, it's a type of exponential function
If can be used for both growth and decay right?
yes
when k > 0, it's growth. When k < 0, it's decay
If you use the formula P0a^t, then growth is for a>1 and decay is for a < 1
The link between the two is :
P0a^t = P0e^(ln(a)t)
Sorry if I'm annoying you with my questions I just wanna write it down
Should I plug it in for t
yep
if you plug in t=7
by definition, P(7) = P0e^(7k)

