# Integration by substituting

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#1
This is completely wrong but idk where I went wrong
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#2
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1 month ago
#3
I can't see any attachments.
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1 month ago
#4
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)
Last edited by mqb2766; 1 month ago
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#5
(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
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1 month ago
#6
(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!
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#7
(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!
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1 month ago
#8
The frist and second terms must involve a root.

So ^7/2 for the first and ^5/2 for the scond
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#9
(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
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1 month ago
#10
(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.
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#11
(Original post by mqb2766)
Write that out explicitly and upload.
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1 month ago
#12
You have to multiply
u^2 + 4u + 4
by
u^(1/2)
first, then integrate.
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#13
(Original post by mqb2766)
You have to multiply
u^2 + 4u + 4
by
u^(1/2)
first, then integrate.
I’ll try that
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#14
(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
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1 month ago
#15
(Original post by Heixi)
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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