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Integration by substituting

This is completely wrong but idk where I went wrong
Reply 1
Avatar for Heixi
Heixi
OP
11
image.jpg
I can't see any attachments.
Reply 3
Avatar for mqb2766
mqb2766
21
You could expand the brackets (penultimate line) then integrate. You seem to have missed out the u^(1/2) multiplier to two of the terms and the last term should be ^(3/2) not ^(1/2)
An alternative substitution is u = sqrt(x-2)
(edited 2 years ago)
Reply 4
Avatar for Heixi
Heixi
OP
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Original post by mqb2766
You could expand the brackets (penultimate line) then integrate. You seem to have missed out the u^(1/2) multiplier to two of the terms?
An alternative substitution is u = sqrt(x-2)

Yeah I just realised that now , imma do it again
Original post by Heixi
This is completely wrong but idk where I went wrong

Your substitution is right, there is nothing to complain, but it gets even simpler: u = sqrt(x-2). Consider the square root too!
Reply 6
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Heixi
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11
Original post by Kallisto
Your substitution is right, there is nothing to complain, but it gets even simpler: u = sqrt(x-2). Consider the square root too!

8E8408F2-D1D4-45CC-86A3-98F57DEF7D13.jpeg
Reply 7
Avatar for mqb2766
mqb2766
21
The frist and second terms must involve a root.

So ^7/2 for the first and ^5/2 for the scond
Reply 8
Avatar for Heixi
Heixi
OP
11
Original post by mqb2766
The frist and second terms must involve a root.

So ^7/2 for the first and ^5/2 for the scond

Why is that the case
If I expand the bracket and then integrate it doesn’t give me that
Reply 9
Avatar for mqb2766
mqb2766
21
Original post by Heixi
Why is that the case
If I expand the bracket and then integrate it doesn’t give me that

Write that out explicitly and upload.
Reply 10
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Heixi
OP
11
Original post by mqb2766
Write that out explicitly and upload.

image.jpg
You have to multiply
u^2 + 4u + 4
by
u^(1/2)
first, then integrate.
Reply 12
Avatar for Heixi
Heixi
OP
11
Original post by mqb2766
You have to multiply
u^2 + 4u + 4
by
u^(1/2)
first, then integrate.


I’ll try that
Reply 13
Avatar for Heixi
Heixi
OP
11
Original post by Heixi
I’ll try that


Original post by mqb2766
You have to multiply
u^2 + 4u + 4
by
u^(1/2)
first, then integrate.

I’ve got it . Thanks
Original post by Heixi
image.jpg


There is a mistake in integration for u^2 + 4u + 4. 4u integrated is 2u^2 (not 4u^2) and 4 is 4u (not 8). Anyway four integration is too soon: you forgot to multiply with u^1/2 before integration!

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