#help-17

1 messages · Page 290 of 1

tidal salmon
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no?

azure fox
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with 15 and 20

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so

tidal salmon
#

you can use the same similar triangles

azure fox
#

huh

tidal salmon
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remember you solved for b

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read through this lol

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i explain every step

azure fox
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so wait

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i need to find the ratio

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?

tidal salmon
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yup

azure fox
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so it would be uhhh

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wait

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would it be like

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the bottom and the c side thing

tidal salmon
#

remember with similar triangles, 16/20 = 12/d = 20/c

azure fox
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ohhhhhhhhh

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so now i have to do the other one

tidal salmon
#

since both the triangles have the same angles

azure fox
#

i feel like i know what i gotta do its just not there

tidal salmon
azure fox
#

yeah

tidal salmon
#

yup

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d=15, like you got before

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so do the same thing with c

azure fox
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so 12/d = 20/c

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wait

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no i can do the

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16 ratio

tidal salmon
tidal salmon
azure fox
#

hmm so

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16/20 = 20/c

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16c = 400

tidal salmon
#

yup

azure fox
#

25

tidal salmon
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yup

azure fox
#

ohh i understand it now

tidal salmon
#

yea

azure fox
#

i had to make the ratios first

tidal salmon
#

mhm

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for a, you can solve in two ways

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the simple way is obvious

azure fox
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subtract

tidal salmon
#

c = 16+a

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or

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you can use similar triangles again

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since the other side is another similar triangle to the big one

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they share the right angle and Z this time

tidal salmon
azure fox
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so 9

tidal salmon
#

yup

azure fox
#

c = 16 + a

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wait how do you get that eqaution tho

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oh nvm

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im stupid

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dont answer that

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so would be like

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7 - x / 13 - x

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x^2 + 5 / x^2 + 20

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i gotta multiply

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then factor

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this one easy

tidal salmon
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yup

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lemme know if u get stuck

azure fox
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5/2 and -5

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i think both are reasonable

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because

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none ends up

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negative

tidal salmon
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you asking me to verify?

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@azure fox if you dont have any more questions, can you say .close

azure fox
#

.close

vocal sleetBOT
#
Channel closed

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Use .reopen if this was a mistake.

vocal sleetBOT
#
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brittle zodiac
#

WHATS MY R FOR 7 IM GONNA CRASH OUT

vocal sleetBOT
hoary blaze
#

isn't it e minus when ln(x) = 0? maybe i'm stupid idk

tropic reef
#

maybe i am stupid too

vague chasm
tropic reef
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yaa

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and minus e ??

hoary blaze
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nah e - 1

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that's the inner radius (idk what it's actually called)

vocal sleetBOT
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@brittle zodiac Has your question been resolved?

brittle zodiac
#

<@&286206848099549185>

#

i tried using every r i can think of and nothing worked

vocal sleetBOT
#

@brittle zodiac Has your question been resolved?

vocal sleetBOT
#
Channel closed

Closed due to timeout

Use .reopen if this was a mistake.

vocal sleetBOT
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Available help channel!

Send your question here to claim the channel.

Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

dense jacinth
#

can anyone explain me how to know, if i should define 2 variables by t and s or if i should do one variable by t

dense jacinth
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im gonna be back in like 15 minutes

dense jacinth
#

back

atomic pine
dense jacinth
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but

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the first one is degenerate too right

atomic pine
dense jacinth
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by degenerate do you mean the variables or the 0=0

atomic pine
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in some sense, I gives some restrictions, II gives MORE restrictions on top of I

atomic pine
#

Firstly let us name our equations A_1, A_2,..., A_n (n equations) instead of I,II, for simplicity sake

dense jacinth
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yeah

atomic pine
#

So you know, in the second example: A_1+4A_2 gives you the "degenerate equation" 0=0 right?

dense jacinth
#

yes sir

atomic pine
#

in general if, there is a combination c_1 A_1+c_2A_2+...+c_nA_n (well we have to make sure c_1,...,c_n are not all 0's), that gives you "0=0" we say A_1,...,A_n contains degeneracy

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for your first example, we can say I, and II does not contain degeneracy, since aI+bII gives you the equation 0=0 if and only if a=b=0

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this might be too much notation at once thrown at youmonkaS

dense jacinth
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i just dont understand how to know what to do

atomic pine
atomic pine
#

for example, a+b=1, and a+b=2 is impossible to solve since A_1-A_2 gives you 0=1

dense jacinth
#

yeah

atomic pine
#

Here is a very neat fact: if $A_1,...,A_n$ are linear equation (not degenerate or impossible) with m variables, then we must have $n\leq m$ and the number of variables we need to introduce is precisely $m-n$

twin meteorBOT
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qwertytrewq

atomic pine
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you can think of each non-degenerate equations as "removing one variable of freedom"

atomic pine
#

in the second example, I is the same as II, so you are just removing one "variables of freedom" so you will need to define 2 variables.

dense jacinth
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i got that

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i understood

atomic pine
dense jacinth
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so in the first example is ent

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sent

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u basically try to express every variable through t?

atomic pine
atomic pine
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because you have freedom over the value of z.

atomic pine
atomic pine
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but you can only choose 1, since you can express everything else in terms of x (or z)

dense jacinth
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i have an exam in 30 minutes

atomic pine
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you do it by "reduction"

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it is a method of getting rid of unwanted terms

dense jacinth
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yeah just eliminate u mean

atomic pine
atomic pine
#

@dense jacinth can you try and do that?

dense jacinth
atomic pine
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Ill provide another example in the meanwhile

dense jacinth
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yeah so multiply the first equation by 2?

atomic pine
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maybe I should be more clear on the procedure

dense jacinth
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i can get rid of c and d

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if i do that

atomic pine
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to keep things organized

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so we subtract A_2 with cA_1 to get a new equation B_2 where B_2 does not have "a" in it

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what would c be?

dense jacinth
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whats cA_1?

atomic pine
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like I-2II

dense jacinth
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oh

atomic pine
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the "2" in "2II"

dense jacinth
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c+d=-4

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?

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-c-d*

atomic pine
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5-1

atomic pine
dense jacinth
atomic pine
#

here is a neat fact: Solving A_1,A_2,A_3 is the same as solving A_1,B_2,A_3

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so solving a+b+c+d=1, a+b+2c+2d=5, 2a+2b+c+d=-2 is the same as solving a+b+c+d=1,c+d=4,2a+2b+c+d=-2

#

now can you use A_1 to "reduce" A_3 (remove the occurence of a in A_3 by subtracting some copies of A_1)

dense jacinth
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uhh

atomic pine
atomic pine
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how many copies of A_1 do you need to subtract from A_3?

dense jacinth
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oh

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ok waot

atomic pine
dense jacinth
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yeah the A_2

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stiff

atomic pine
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pls lmk where you got confused on

dense jacinth
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😭

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i dont get what the A is about

atomic pine
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Im numbering the equations 1,2,3 and denoting them as A_1, A_2, A_3

dense jacinth
#

oh

atomic pine
#

so A_1 is the equation a+b+c+d=1, A_2 is a+b+2c+2d=5, A_3 is 2a+2b+c+d=-2

atomic pine
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our first step is to get rid of the a's from A_2 (using only A_1) so we subtracted one copy of A_1

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so we got a new equation B_2 which is c+d=4

atomic pine
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A_3-2A_1 is?

dense jacinth
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ill be right back

atomic pine
dense jacinth
dense jacinth
atomic pine
#

2a+2b+c+d- 2(a+b+c+d)=-2-2

dense jacinth
#

oh

dense jacinth
atomic pine
dense jacinth
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ohhh

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shit

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-4

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😭

atomic pine
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yeah so you get -c-d=0

dense jacinth
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yeah

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we also have the other

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thing

atomic pine
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so the neat fact tell us that solving for A_1,A_2,A_3 is equivalent to solving A_1, c+d=4, and -c-d=-4

dense jacinth
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OHHH

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yes

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i understand

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like understand that it makes sense

atomic pine
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the next step is to organize our equations

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and order it by leading terms

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so in this case we don't need to order it

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since a+b+c+d=1, c+d=4, -c-d=-4 is already ordered by the leading term

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we now can take the second equation, and ask the same questions: How can I remover "c" (the leading term of the second equation) from both A_1, and the third eqution

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So if we set B_1 to be a+b+c+d=1, B_2 to be c+d=4, B_3 to be -c-d=-4, we need to reduce B_1, and B_3 using B_2

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I'll save you the trouble and tell you that you will get a+b=-3, c+d=4, and 0=0

atomic pine
dense jacinth
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my bad

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i was gond

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im bacj

atomic pine
#

So the steps are:

  1. Order your equations by the leading terms
  2. take the first equation, and use that equation to "reduce" the other equations (so that the leading term of the first equation does not appear on the rest)
  3. Order your equations again.
  4. Take the second equations, and use that equation to "reduce" the other equations (so the the leading term of the second equation does not appear on the rest)
  5. rinse and repeat
dense jacinth
#

but i think he wont do 4x3 system

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only 3x2

atomic pine
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if you have more equations, then you may need to do more steps

dense jacinth
atomic pine
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but this strategy works for all system of linear equations (after the process, you will ALWAYS end up with a nice system of equations)

dense jacinth
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this is an overdefined system

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can u maybe summarize me

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how to go forward on these

atomic pine
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order the equations first (in this case there is no need in ordering the equations since they all start at x)

atomic pine
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you should get ||0=0 and 0=-1||

dense jacinth
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wait ill be right back

dense jacinth
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i mean the solution is on the screenshot😭

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i would just do it like how my teacher did it

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but 1 thing i dont understand,

atomic pine
#

(it might be more difficult to just "play around and find a way to reduce" compared to a systematic way of reducing our equations)

atomic pine
dense jacinth
dense jacinth
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like usual

atomic pine
atomic pine
#

this is saying "if x,y satisfy I, III, then 0=2"

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but this cannot be, so there cannot be any simultaneous solutions to I and II

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I, II gives you degeneracy, but I,III give you an impossible solution

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so I,II,III cannot have solution simultaneously

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GL on your exam

dense jacinth
atomic pine
dense jacinth
atomic pine
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Oh

dense jacinth
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i understand it ngl

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theres a chance the test is more focused on trigonomic functions

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which im better at kinda

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ok so generally

atomic pine
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good stuff

dense jacinth
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if we have a 3x4 system

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i mean

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4x3

atomic pine
# dense jacinth 4x3

you just do this process over and over again: ditch every 0=0 you see, and whenever you see 0=1 or 0=some non-zero value, you would know that there is no solution

dense jacinth
#

but we could get single values for x y and z right

atomic pine
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for example the system of equations x=1, y=2, z=3

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has single value solutions

dense jacinth
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yeah

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i doubt that 4x3 gonna come tho

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we never did that

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but maybe

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😭

atomic pine
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5*4, 5*5,...., you name it

dense jacinth
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wait so

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i can just memorize

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a overdefined function cant have unlimited solutions?

atomic pine
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x=1, x=1, x=1, x=1, x=1 is overdefined

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but they still have the solution x=1

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if a overdefined system of equations do not contain degeneracy, then it will never have solutions. (overdefined means there are strictly more equations than variables)

dense jacinth
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yeah here for example

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idk why hes calling the first eqution boss 😭

atomic pine
dense jacinth
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i think

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we did it so

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we like kind of neglect a function

atomic pine
# dense jacinth

again you just apply the same rules: reduce II and III using the equation I

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and you realize II and III gets reduces to 0=0

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so by the "neat fact" I stated a while back, it just suffices to solve equation I

dense jacinth
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can you like write down what u mean by reduce II and III using the equation I

atomic pine
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so II+2/3 I

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and III- 1/3 I

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you get 0=0 and 0=0

dense jacinth
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oh

atomic pine
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the 2nd step says: take the first equation and remove "x" from II and III

dense jacinth
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why did he stop at 0=0

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i dont understand 😭

atomic pine
dense jacinth
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ohh

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so herr

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every line gives 0=0

atomic pine
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anyway what he is saying is I, II, III are essentially the same equations

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so we just need to solve for I

atomic pine
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we "reduce" II and III from I

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we get 0=0, throw them out.

atomic pine
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and see what answer you get.

vocal sleetBOT
#

@dense jacinth Has your question been resolved?

dense jacinth
#

the differnece here is

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that the one is infinite

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as solution

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omg

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i understand now

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the one is infinite and the other one with the z=t

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is also infinite?

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or what is ot

vocal sleetBOT
#
Channel closed

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#
Available help channel!

Send your question here to claim the channel.

Remember:
Ask your math question in a clear, concise manner.
Show your work, and if possible, explain where you are stuck.
After 15 minutes, feel free to ping <@&286206848099549185>.
• Type the command .close to free the channel when you're done.
• Be polite and have a nice day!

Read #❓how-to-get-help for further information on how to ask a good question, and about conduct in the question channels.

ripe iron
vocal sleetBOT
paper depot
#

omg is that the old notation for factorials

ripe iron
#

@worthy ridge

#

<@&286206848099549185>

paper depot
vocal sleetBOT
ripe iron
worthy ridge
ripe iron
#

lmao

hybrid rampart
#

yo can i grab a hand

paper depot
vocal sleetBOT
#

@ripe iron Has your question been resolved?

peak matrix
#

I somehow managed to show that it equals this sum:
$\sum_{k=1}^n \binom{2k}{k} \cdot 4^{-k} = \sum_{k=1}^n \binom{-\frac{1}{2}}{k} \cdot (-1)^{k}$

twin meteorBOT
#

MathIsAlwaysRight

peak matrix
#

idk if thats any helpful tho

ripe iron
#

what

paper depot
#

it would be much easier if it said to find the sum to infinity

peak matrix
#

it diverges, doesnt it?

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I just tried putting it into wolfram alpha

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it gives a closed form

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it's pretty ugly tho

ripe iron
#

we should create a telescopic series

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sheesh

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ig no one knows how to solve

vocal sleetBOT
#

@ripe iron Has your question been resolved?

vocal sleetBOT
#

@ripe iron Has your question been resolved?

neat rose
#

@ripe iron whats the question

ripe iron
neat rose
#

what the gibberish?

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make a valid question

elder mountain
#

wtf

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Ask chat gpt

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Idfk

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Js say bismlah and move on

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😭

ripe iron
#

tht is just factoril

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factorial

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its the old notation for factorial

neat rose
#

yeah, use latex to create a valid modern question

ripe iron
#

ugh

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fine

#

$\frac{1}{1!}(\frac{1}{2}) +\frac{1.3}{2!}(\frac{1}{2})^2 +\frac{1.3.5}{3!}(\frac{1}{2})^3 + \dots \text{upto n terms is..}$

twin meteorBOT
ripe iron
#

@neat rose

neat rose
#

try harder make it something more readable

ripe iron
#

i got better things to do

neat rose
#

same here

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good luck

ripe iron
#

:/

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thanks ig

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gl to you aswell

vocal sleetBOT
#

@ripe iron Has your question been resolved?

paper depot
vocal sleetBOT
# elder mountain Ask chat gpt

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

elder mountain
paper depot
#

they often generate output which "sounds correct" but has numerous factual or logical errors.

paper depot
#

if you wanna argue this, go to #discussion or something.

#

somebody else's help channel is not the place.

elder mountain
#

Look no chat gpt go to deep seek

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Dug

paper depot
#

can also call the mods if you really want to argue.

elder mountain
#

Yeh cool

paper depot
#

actually yeah <@&268886789983436800> we got someone here who knows more about our own rules than us

elder mountain
#

U did say no chat GPT but no deep seek

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Anyway

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Imma chill

#

Bye 😘

versed bane
#

if people wanted to use AI, they would just use it and not come here.

elder mountain
#

Ig

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Anyway

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U can also use daddy khan

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He always comes to the rescue

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Imma gamble my sons child support

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🎀

flat whale
#

if you're not gonna help, can you not spam OP's help channel

elder mountain
#

K yall r sooo boring 🥱

#

Bye bye ig

topaz eagle
#

you may try to comprehend
the partial sums can be rewritten as a trigonometric polynomial (with degree 2n)

#

you'll transform the partial sum
1/2 + 1 ⋅ 3 / (2 ⋅ 4) + 1 ⋅ 3 ⋅ 5 / (2 ⋅ 4 ⋅ 6) + ⋯ + 1 ⋅ 3 ⋯ (2n − 1) / (2 ⋅ 4 ⋯ (2n))
to an integral with the integrand
cos² x + cos⁴ x + cos⁶ x + ⋯ + cos² x

topaz eagle
#

You may try to use some math to capture the graphical observation that "the peak gets higher and higher"

topaz eagle
#

hint: ||for any δ > 0, consider the sequence of definite integrals whose integrand is cos² x + cos⁴ x + cos⁶ x + ⋯ + cos² x over [δ, π / 2]. (think: why do we want to do so?) the integrand forms a sequence of functions. it's easy to establish uniform convergence to its pointwise limit. in fact, the integral of this pointwise limit over [δ, π / 2] is actually the limit value of this sequence of definite integrals. the rest shld b easy||

vocal sleetBOT
#

@ripe iron Has your question been resolved?

ripe iron
#

XD

topaz eagle
#

the desmos graph is just to provide a graphical intuition
and you can sketch a similar graph without any calculator

topaz eagle
#

you just need to substitute x = 0 into the integrand to observe this phenomenon

as n gets "larger and larger", the peak gets "higher and higher"

candid magnet
ripe iron
topaz eagle
ripe iron
#

btw i got the answer from elsewhere

#

im just seeing if someone else cracks it

#

is that against the server rules or something

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then ill take it down

candid magnet
#

no

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its not

ripe iron
#

ok

candid magnet
ripe iron
#

its in hindi

candid magnet
#

i can understand a bit

ripe iron
#

sure

#
#

question number 4

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in the

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time stamp

candid magnet
#

i think u shld be able to do it in the way

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the perosn above mentioned

topaz eagle
#

I misread the question

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I thought it's to find the limit value of this infinite series, by only looking at the symbols

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I don't think there's an easy way to evaluate the integrand for any partial sum above

candid magnet
#

i think u can

#

get it

#

let me try

#

@ripe iron

#

,rccw

twin meteorBOT
candid magnet
#

honestly it was basically that guys idea

ripe iron
#

yeah i understood his idea

#

what

#

how do you haave pi

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in your answer

candid magnet
#

when u open the integration with wallis u get this

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multipled by pi /2

ripe iron
#

this is crazy stuff

#

man

#

your smart

candid magnet
#

honestly it was his idea

#

there was like a tougher version of this

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in the adv sample paper they released for 2025

ripe iron
#

u in 12th>

#

?

candid magnet
#

ye

ripe iron
#

damn gl man

candid magnet
#

thanks

ripe iron
#

how was mains(if you dont mind me asking)

candid magnet
#

honestly it was bad

#

mains so annoying with those terrible

#

calculations

ripe iron
#

yeah its a pain

#

im in 11th

candid magnet
#

ic

ripe iron
#

2026 aspirant

candid magnet
#

which college if u dont mind

ripe iron
#

iit kgp

candid magnet
#

i meant

ripe iron
#

possibly

candid magnet
#

like rn

ripe iron
#

college?

candid magnet
#

school

ripe iron
#

oh

#

im in kerala

#

st vincent

candid magnet
#

ic

ripe iron
#

wby

candid magnet
#

fiitjee

ripe iron
#

oh

#

damn delhi>

#

?

candid magnet
#

no telengana

ripe iron
#

im in brilliant pala

#

hmm

candid magnet
#

fiitjee has many branches

ripe iron
#

st vincent is my school not coaching lma

candid magnet
#

ic

#

fiitjee

#

is like both here

ripe iron
candid magnet
#

school plus coaching

ripe iron
#

i dont go to school

candid magnet
#

they only do both

ripe iron
#

lmao

candid magnet
#

honestly doesnt matter

#

if ur coaching is good

ripe iron
#

yeah its alright

#

i mean its not the best

#

or anything

#

but its ok

#

once we had an air 3

candid magnet
#

understandable

ripe iron
#

once

candid magnet
#

mine is also somwhere along that

ripe iron
#

in 2020 or something

#

i dont know for sure

candid magnet
#

its not thta good compared to delhi

ripe iron
#

there is a fitjee near my place

candid magnet
ripe iron
#

also

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i dont go there

candid magnet
#

oh

#

lmao

ripe iron
candid magnet
#

ic

ripe iron
#

and lbh air under 10s have some special formulas

#

lol

candid magnet
#

real

#

u just got be born different

ripe iron
#

fr

candid magnet
#

no offence but like

ripe iron
#

theres one dude here bro just gets every single question

#

idk how

candid magnet
#

air under 10 is just ur born smart hard work only takes u so far

ripe iron
#

some guy here preparing from 6th

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its crazy

#

no life

candid magnet
#

i started in 11th

ripe iron
#

same

candid magnet
#

and its already depressing enough

#

i couldnt imagine like 4 more yrs

ripe iron
#

yeh fr

candid magnet
#

than this

ripe iron
#

anyway man

#

gl

candid magnet
#

thanks bye

#

close the channel

ripe iron
#

go get iit

#

hmm

candid magnet
#

if ur done with it

#

i try

ripe iron
#

.close

vocal sleetBOT
#
Channel closed

Closed by @ripe iron

Use .reopen if this was a mistake.

vocal sleetBOT
#
Available help channel!

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• Be polite and have a nice day!

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bleak prawn
vocal sleetBOT
bleak prawn
#

u = 256 - x^2

atomic jasper
#

continue

bleak prawn
#

du = -2xdx

#

-(x*sqrt(u))/2x

#

-sqrt(u)/2

wary hull
atomic jasper
#

continue

atomic jasper
vocal sleetBOT
# wary hull 4096/3

As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.

bleak prawn
#

-(u^1/2)/2

atomic jasper
#

that is the same thing, yes

bleak prawn
#

Oh wait

#

I think I see my mistake

#

1 moment

atomic jasper
#

did you forget the bounds?

bleak prawn
#

Ummm I did make a mistake but I still didnt get the right answer

#

So ill just continue

atomic jasper
#

can you show your derivation?

bleak prawn
atomic jasper
#

your working out

bleak prawn
#

Ah I just typed it haha so not really its deleted

atomic jasper
#

...

#

are you never writing these down?

bleak prawn
#

Sometimes I do

#

-(u^1/2)/2

atomic jasper
#

you should almost always write it donw

bleak prawn
#

Integrates to
-2(u^3/2)/2(3)

#

-(u^3/2)/3

atomic jasper
#

yes

bleak prawn
#

Which is negative...

atomic jasper
bleak prawn
#

Ok, I dont understand the bounds thing

#

Last time I did it and they told me not to do it

atomic jasper
#

the bounds are from x=0 to x=16

bleak prawn
#

1 moment ill find the chat

atomic jasper
#

but now we have u=256-x^2

#

if we fill in x=0 and x=16

#

we get the new bounds: from u=256 to u=0

#

u=256-0^2=256
u=256-16^2=256-256=0

atomic jasper
bleak prawn
#

I cant find it 😡

#

But yeah I did it and got the wrong answer, then they told me not to do the bounds and I got the right answer

atomic jasper
#

i cant think of a context where you dont change the bounds

bleak prawn
#

So now im lostttt

#

1 moment ill search again

atomic jasper
#

does what i wrote make sense?

bleak prawn
#

Found it

atomic jasper
#

there you also plug in the bounds lol

bleak prawn
atomic jasper
#

i dont see the issue

#

you first had 0 to pi/2

#

then you had 0 to 1

#

?

bleak prawn
#

Yes and it was wrong

atomic jasper
#

thats changing the bounds

bleak prawn
#

They wanted to just leave it as pi/2

#

Wait I will find that question again 1 moment

atomic jasper
#

oh i see now

#

i suppose you can do the whole calculation without changing the bounds

#

but you have to be precise with what youre doing

#

also, trig subs are quite a bit different and tricky sometimes

bleak prawn
atomic jasper
#

you got -u^(3/2)/3

#

if you dont change the bounds

#

then you need to fill back in u=256-x^2

#

to get -(256-x^2)^(3/2)/3 from 0 to 16

#

if you do change the bounds, then you can keep it at it was before

#

make sense?

bleak prawn
atomic jasper
empty frigate
#

yeah the issue isn't exactly that you did or didn't change the bounds, it's that you weren't consistent with what you were doing

bleak prawn
#

Like we need to convert it from u no matter what

atomic jasper
#

you dont necessarily need to

#

you can keep it in terms of u

bleak prawn
empty frigate
#

if you take bounds of u=0 to u=1, and plug it into u^3/3 - u^5/5, that's fine

bleak prawn
atomic jasper
#

if oyu wanna be super precise you should do $\int_{x=0}^{x=16} \frac{-\sqrt{u(x)}}{2}\dd u(x)$

empty frigate
twin meteorBOT
empty frigate
atomic jasper
#

then you get $\left[\frac{-u(x)^{\frac32}}{3}\right]_{x=0}^{x=16}$

twin meteorBOT
bleak prawn
atomic jasper
#

we are not plugging in u=0 and u=16

bleak prawn
#

So I DO take the bounds

#

For this one

empty frigate
#

...

atomic jasper
#

we are plugging in u(0) and u(16)

empty frigate
#

there are two approaches that work

atomic jasper
empty frigate
atomic jasper
#

does this combo make sense?

empty frigate
#

it's just that you're instead using an approach that never works, by mixing the two approaches in a way that doesn't make sense

empty frigate
#

-# yeah occasionally it will get you the right answer by numerical coincidence, or because the bounds wouldn't have been updated anyway, but still

#

if the bounds you have are x=0 to x=16, then you evaluate those bounds at a function of x

atomic jasper
#

i can show you the general form i foyu like odie

empty frigate
#

pick one of those two messages and follow through with it the whole way, don't try to do both at the same time

bleak prawn
#

The thing im confused about is I feel like I used the same method for both of them. With the trig example if I took the bounds 1 and 0 (changing the bounds) I got the wrong answer. If I DIDNT change them, taking pi/2 and 0, I got the right answer.
For this question, if I DIDNT change the bounds (0 and 16) I got the wrong answer. if I DO change them (0 and 256) I got the right answer. Im confuseddddd

atomic jasper
#

or you misunderstood smth

#

we can go through the general form if youd like

bleak prawn
#

sin^2(x)cos^3(x)
sin^2(x)(1-sin^2(x))cos(x)
(sin^2(x)-sin^4(x))cos(x)
u = sin(x)
du = cos(x)dx
u^2 - u^4
Integrates to (u^3)/3 - (u^5)/5
The bounds also change due to the integration u = sin(x)
sin(pi/2) = 1
sin(0) = 0
so the final sum is:
sin^3(1)/3 - sin^5(0)/5

bleak prawn
#

It gave the wrong answer so I must have done something wrong

empty frigate
#

"1 to 0" is bounds in terms of u, which means you put them into u^3/3 - u^5/5, because that's the result in terms of u

atomic jasper
#

first you have u, then you use x

#

your u bounds are from 1 to 0

#

your x bounds are from 0 to pi/2

#

you changed the bounds correctly to the u bounds

#

but then you filled in the x equation

bleak prawn
#

So it should be sin^3(sin(x))/3 ?

atomic jasper
#

its either $\left.u^3/3-u^5/5\right|_1^0$ or $\left.\sin(x)^3/3-\sin(x)^5/5\right|_0^{\pi/2}$

twin meteorBOT
atomic jasper
#

you took the formula with x, and the bounds of u

bleak prawn
#

1 moment im just rereading everything 100 times 😵‍💫

atomic jasper
#

if you have a question, just ask

bleak prawn
atomic jasper
#

you sure?

#

i think we can bang it out in 10 minutes

#

for every integral

#

(general form)

bleak prawn
#

Tbh I think youve explained it in a way I can understand already, my brain just isnt functioning at this hour LOL

#

If I reread all this tomorrow morning I think ill be able to get it

atomic jasper
#

100%?

bleak prawn
#

Yeah I think so haha

#

But thank you both for your help until this point!!

atomic jasper
#

alrighty

bleak prawn
#

❤️

#

.close

vocal sleetBOT
#
Channel closed

Closed by @bleak prawn

Use .reopen if this was a mistake.

atomic jasper
#

gn!

#

(in advance)

bleak prawn
#

Tot morgen hehe

atomic jasper
#

:p

vocal sleetBOT
#
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vast shale
#

how solve this with integration by parts

vocal sleetBOT
vast shale
#

With usub it is easy

#

i dont get how this is possible with int by parts tho

regal bane
#

Do you know that it can be done?

vast shale
#

yes

#

yeah nvm

#

its stupid

#

.clode

#

.close

vocal sleetBOT
#
Channel closed

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vast shale
#

hey guys i have a questio

#

question

#

how do you solve this with integration by parts

regal bane
#

In this case, you take the derivative of 3-x, and the integral of e^2x

#

Much simpler integral after that

vocal sleetBOT
#
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pseudo rapids
#

The grades of 300 students are normally distributed with a mean of 50 and a standard deviation of 5. 60 students were higher than Paul. What grade did Paul get?

pseudo rapids
#

i found the Z score

#

its 2

livid lodge
#

i learnt this last year but wasnt here so idk

#

can u look at mine tho

#

cause i tried urs so

pseudo rapids
#

bro idk

#

just ask chatgpt

#

its easy

quiet echo
vocal sleetBOT
# pseudo rapids just ask chatgpt

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

pseudo rapids
#

@quiet echo can you help me?

quiet echo
pseudo rapids
#

@open sundial

#

<@&286206848099549185>

coral chasm
#

60 were higher than paul which means 60/300 or 20% of the population is higher than him which means paul is in the 80th percentile. Get the z score of the 80th percentile and just use the z score formula

pseudo rapids
#

om g thxcx

#

dadd

#

0.84

coral chasm
#

Then use this

pseudo rapids
#

0,84 = (300-p)/5

coral chasm
#

Yes

pseudo rapids
#

im getting -295,8

coral chasm
#

Wait, no

#

It should be 0.84 = (x - 50)/5

pseudo rapids
#

we dont know his mean grade

coral chasm
#

The mean that is referring to is the mean of the population

#

Which is given

pseudo rapids
#

fine i.g..

#

.close

vocal sleetBOT
#
Channel closed

Closed by @pseudo rapids

Use .reopen if this was a mistake.

pseudo rapids
#

.close

vocal sleetBOT
#
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sage wind
vocal sleetBOT
sage wind
#

isnt this question solved directly by using the theorem that i posted?

#

just apply theorem 3.50 to Σ|a_n|, Σ|b_n| and Σ|c_n| with c_n given as in 3.50

regal bane
#

No, since 3.50 assumes both converge, but the question only assumes one does

#

absolutely*

sage wind
#

but if the sum converges absolutely then it converges

regal bane
#

The question is basically asking "why does the cauchy product fail if we don't assume absolute convergence?"

#

Or, well, prove it fails

#

OH sorry, I have the pictures swapped

sage wind
sage wind
regal bane
#

My issue is that 3.50 doesn't say the cauchy product converges absolutely

#

Just that it "converges" which is annoyingly vague

sage wind
#

yes but you are given that Σ|a_n| and Σ|b_n| converge, you also know that Σ|a_n| converges absolutely since Σ|a_n|=Σ| |a_n| |

#

so replace Σa_n by Σ|a_n| and Σb_n by Σ|b_n| in 3.50

#

then c_n=Σ|a_kb_{n-k}|

#

so that Σ|c_n|=Σ| Σ|a_kb_{n-k}||=ΣΣ|a_kb_{n-k}|=Σc_n which is convergent

#

this means that Σc_n converges absolutely no ?

vocal sleetBOT
#

@sage wind Has your question been resolved?

vocal sleetBOT
#

@sage wind Has your question been resolved?

vocal sleetBOT
#
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#
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tawny nacelle
#

okay, quick question

vocal sleetBOT
tawny nacelle
#

I have started this proof as so

#

now, I cannot simply say that F is smooth because each component is smooth, right?

silk rampart
#

starry

#

hello

#

idk what ur studying so i cant help u with this

#

so can u tell me what u are studying

tawny nacelle
#

and then show that that is smooth

#

is that correct?

tawny nacelle
gusty cobalt
#

write in differential geometry

silk rampart
#

that sounds advanced

#

good luck

gusty cobalt
#

these are for pre-uni

tawny nacelle
#

I am allowed to ask here

gusty cobalt
#

• These channels are for pre-university homework-type questions. Broad conceptual questions, as well as questions in university-level topics — are more appropriate in topic-specific channels (Pre-University, Early University, Advanced Mathematics) and in ⁠math-discussion.

tawny nacelle
gusty cobalt
#

but sure

tawny nacelle
#

but I choose to ask here anyways

inner osprey
#

we really need to do away with that section of text

tawny nacelle
#

meta suggestion ig

jagged cargo
livid summit
#

find charts of both manifolds and show the map is smooth in these coordinates

#

thats all

tawny nacelle
livid summit
#

it doesnt even need to be all combinations of charts

tawny nacelle
#

just one

#

one pair of charts

livid summit
#

one pair of charts, as long as you have enough charts to cover the domain

tawny nacelle
#

I'm 100% sure we do thumbsupanimegirl

#

thanks metal, and happy birthday aecatheart

#

.solved

vocal sleetBOT
#
Channel closed

Closed by @tawny nacelle

Use .reopen if this was a mistake.

livid summit
#

ty

vocal sleetBOT
#
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ember verge
vocal sleetBOT
ember verge
#

im supposed to evaluate this

livid lodge
#

bro

ember verge
#

i thought it would be 1/2 ln e

livid lodge
#

can someon ehelp me

ember verge
#

so 1/2

livid lodge
#

ive been waititng for years

#

help-25

heavy yoke
#

!noad

ember verge
#

the ans is 2

gusty cobalt
shut canyon
#

its wrong you can check on calculator

heavy yoke
#

the answer key is wrong unfortunately

shut canyon
#

1/2 is correcy

#

correct

ember verge
#

oh ok

#

ty

hallow meteor
# ember verge

are you sure you didn't accidentally check the answer for the second question

ember verge
#

also the first two were right

#

idk why

hallow meteor
#

alright cool

#

just making sure

ember verge
#

ty anyway

#

.close

vocal sleetBOT
#
Channel closed

Closed by @ember verge

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vocal sleetBOT
#
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vague vessel
vocal sleetBOT
vague vessel
#

Is this right

hallow meteor
#

nope wrong

#

x^7 doesn't have a dx

#

you can't just add it with 6dx

vague vessel
hallow meteor
#

only if all x are with dx

#

its like 5x + 6

vague vessel
#

Then what do with 6

hallow meteor
#

its a different solution

#

wait I'm sorry

#

i got confused cuz you didn't multiply dx with x^7e^y

vague vessel
hallow meteor
#

you forgot a minus

#

final step

#

-e^-y = x+x^8/8 + c

#

you have to multiply by minus to apply ln on both sides

vague vessel
hallow meteor
#

there's a ln on rhs

#

it would be -ln(-6x-x^8/8+c)

vague vessel
hallow meteor
#

yep

vague vessel
#

Ok so it asks for y(0)=5

#

5=-ln(c)?

#

How I find what c is

hallow meteor
#

multiply by minus and take e power on both sides

#

so c = e^-5

vague vessel
hallow meteor
#

to cancel out ln

#

e is the inverse function of ln

#

e^lnx = x

vague vessel
#

Ok so the answer is y= -ln(-6x -x^8/8 + e^-5?

hallow meteor
#

yep

vocal sleetBOT
#

@vague vessel Has your question been resolved?

vocal sleetBOT
#
Channel closed

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#
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finite hatch
#

Hello

vocal sleetBOT
finite hatch
#

How would i put this into the last formula

#

Im confused on the 1/q

#

1/q = 5

gentle sleet
# finite hatch

we want z right?
so we can raise both sides to the 1/5 power

finite hatch
#

oh

#

ok thanks!

gentle sleet
#

np!

finite hatch
#

.close

vocal sleetBOT
#
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vocal sleetBOT
#
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fallow sky
#

can anyone help me with this, its in the 'proof by contradiction' chapter of my textbook and im not very confident in proof and dont know where to start or handle this

fallow sky
#

idk what to do for eitehr

cedar bone
#

What does it mean for a number to be odd?

#

@fallow sky

fallow sky
#

2n

#

2n + 1?

#

sorry i have really bad internet

cedar bone
#

Yep, so Even numbers look like 2n, and odd numbers look like 2n+1. Also, being prime means that its only factors are itself and 1. Keep these definitions in mind. To prove this by contradiction, you first assume the opposite is true: There is an even prime that is > 2

#

Does that much make sense?

fallow sky
#

yeah that all clear

cedar bone
#

Alright, so this number is by assumption even, so what does that say about it?

fallow sky
#

its divisible by 2

cedar bone
#

Yep, but what did we say the definition of prime was?

#

Its not divisible by anything but itself and 1 right?

fallow sky
#

yeah ok cool

#

so we cleared that prime numbers > 2 cant be even

cedar bone
#

Again, let's prove b) by contradiction. What's the opposite of "there are no two primes whose sum is 1001"?

fallow sky
#

there are two primes that add to 1001

cedar bone
#

Yep, and often with these kinds of problems its useful to specify that symbollicaly as well. So one way to do that would be to write that there are two primes p and q such that p+q=1001

#

What can you tell me about 1001 as a number?

fallow sky
#

its odd

cedar bone
#

Perfect

#

If p+q= an odd number, what can you say about p and q?

fallow sky
#

since they are primes they have to be odd since they have to > 2 so that would mean
2n + 1 + (2n + 1) = 2n + 1
4n + 2 = 2n + 1
2(2n + 1) = 2n + 1 which is a contradcition

cedar bone
#

You've got the main idea, but one thing's missing

#

there's an even prime that you need to account for

#

so assume one of p/q is that prime, and show that it still doesnt work

fallow sky
#

ok at this point im a little stuck

cedar bone
#

So you've made the assumption in what you wrote that the primes are >2

#

but ther's one prime that isn't >2, which is 2

#

so you have to account for that separately

#

So assume that one of p or q is in fact 2 (for contradiction)

#

Say p

#

then, q+2=1001

#

with q prime

#

what's wrong with that?

fallow sky
#

q would have to be 999 with isnt prime

cedar bone
#

Perfect

#

That completes it

fallow sky
#

alright so my conclusion statement would be that 2 primes cannot equal an odd intergar and with the exception of 2 it still cannot be

cedar bone
fallow sky
#

alrigth so they all represent a different interger but its showing that the interger its representing is something different for each variable?

cedar bone
cedar bone
fallow sky
#

yeah that makes sense

#

alright cool

#

thanks for the help

cedar bone
#

no worries, best of luck

fallow sky
#

.close

vocal sleetBOT
#
Channel closed

Closed by @fallow sky

Use .reopen if this was a mistake.

vocal sleetBOT
#
Available help channel!

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Ask your math question in a clear, concise manner.
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After 15 minutes, feel free to ping <@&286206848099549185>.
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autumn flax
#

hello, i am currently studying for the Singapore and Asian Schools Math Olympiad, while looong at past paers, i came upun this question which i could not answer

karmic crane
#

try to look at corresponding spots in the first two columns of a given row

#

look what the result is in the third column when both the triangles are facing the same direction, and when they arent

#

or when there is a tringle in one column but not in the other

autumn flax
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I belive its either A or D, dont know exactly

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Im leaning on D

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Tell me if its correct

karmic crane
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D is what I got

autumn flax
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i have some more questions

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First, what is a crypathim

vocal sleetBOT
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@autumn flax Has your question been resolved?

pallid temple
autumn flax
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So, how would the above mentioned crypathim work

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I have to go now, we will talk later

vocal sleetBOT
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@autumn flax Has your question been resolved?

pallid hedge
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The first clue is from g becoming d which means o + d > 9 and g +1 = d

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After that you substitute for o + d = 10 + g

vocal sleetBOT
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turbid snow
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If we have the expression -(x+3)(x-3), does the negative distribute to both terms or only just one?

tidal umbra
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one

languid grotto
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Think of it as (-1)(x+3)(x-3)

turbid snow
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.close