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A-Level Maths Differentiation Question

*INTEGRATION NOT DIFFERENTIATION*
Anyone know how to do this?
(edited 5 years ago)
The question
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That’s an integration question not a differentiation question. Might be a good start 😄.
I’ll have a go at it now and see if I get anywhere
Original post by Jamie_1712
That’s an integration question not a differentiation question. Might be a good start 😄.
I’ll have a go at it now and see if I get anywhere

ah yeah my bad lol
Wow that's crazy I think I've actually done it.

I got the answer 176.55

Substitute the U^2, and then differentiate the expression (You'll have to use implicit differentiation) and rearrange to get into dx terms.
Once you've done that. You can subsitutute x = in terms of u for the numerator.
Pretty simple from there.

EDIT: Haven't done an integration in SO long. But I am studying Maths so I have that going for me lol.
Original post by FailedMyMocks
Wow that's crazy I think I've actually done it.

I got the answer 176.55

Substitute the U^2, and then differentiate the expression (You'll have to use implicit differentiation) and rearrange to get into dx terms.
Once you've done that. You can subsitutute x = in terms of u for the numerator.
Pretty simple from there.

EDIT: Haven't done an integration in SO long. But I am studying Maths so I have that going for me lol.

the answer is 592/3 or 197.3 recurring bro
I’m struggling 😂. Bare with me
Got an answer but it’s wrong
Original post by Jamie_1712
Got an answer but it’s wrong

lol i can post the solution on here but i dont understand it myself...
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Reply 9
Avatar for Sinnoh
Sinnoh
22
Original post by NothingButWaleed
lol i can post the solution on here but i dont understand it myself...


What bit in particular don't you understand?
Reply 10
Avatar for mnnbv
mnnbv
14
image-f1dd8c20-2e56-44f6-8976-2abf14438eb15726082159912147026-compressed.jpg.jpeg

baisically the point of substitution is to make the maths a bit easier to eventually integrate

step 1: find du/dx by differentiating what they said was U (in this example it was implicit differentiation required)
step 2: rearange the the substitution they gave to get x in terms of u
step 3: put the original limits (in this case 20 and 6) into the substitution they gave to get a value of what this would be as U (almost like you are coding the data?)
step 4: shove all that information in to the original so it is all in terms of U
step 5: simplify and then integrate
step 6: party time


also, aplogies if my 4s and Us are confusing! I gotta work on that for my exams😬
(edited 5 years ago)
I got 592/3 for the answer...
Reply 12
Avatar for Notnek
Notnek
21
A reminder that full solutions are against the rules of the maths forum. Please offer hints instead.
but why do you have to implicit differentiate...i differentiated by square rooting both sides to get U= (4x+1)^1/2 and then differentiated that
Reply 14
Avatar for mnnbv
mnnbv
14
Original post by NothingButWaleed
but why do you have to implicit differentiate...i differentiated by square rooting both sides to get U= (4x+1)^1/2 and then differentiated that

Implicit is just a lot faster and simpler in this question. You could of course have done it your way :biggrin:
Original post by mnnbv
Implicit is just a lot faster and simpler in this question. You could of course have done it your way :biggrin:

it doesnt work though..i get dx= du/2(4x+1)^-1/2
Reply 16
Avatar for mnnbv
mnnbv
14
Original post by NothingButWaleed
it doesnt work though..i get dx= du/2(4x+1)^-1/2


substiute u into this- dx= du/2(4x+1)^-1/2
dx= du/2(u^1/2)^-1/2

and then simplify
Original post by mnnbv
substiute u into this- dx= du/2(4x+1)^-1/2
dx= du/2(u^1/2)^-1/2

and then simplify

yeah figured it out haha
but thanks for your help man!
Reply 18
Avatar for mnnbv
mnnbv
14
Original post by NothingButWaleed
yeah figured it out haha
but thanks for your help man!


No worries, I got some integration practise in haha

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