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C3 Integration by Parts Q

Hey,

Can anyone show me the working for integral of x*(1+x)^1/2 using integration by parts and also using substitution u= 1+x? I can't seem to get the right answer :/
Original post by couruthim
Hey,

Can anyone show me the working for integral of x*(1+x)^1/2 using integration by parts and also using substitution u= 1+x? I can't seem to get the right answer :/


What have you tried?
Reply 2
I tried by parts, here's my working:
u= x, v=2/3(x+1)^3/2
du/dx= 1, dv/dx= (x+1)^1/2

2/3x(x+1)^3/2 - integral of 2/3(x+1)^3/2
=2/3x(x+1)^3/2- 4/15(x+1)^5/2 + c
Reply 3
Original post by couruthim
I tried by parts, here's my working:
u= x, v=2/3(x+1)^3/2
du/dx= 1, dv/dx= (x+1)^1/2

2/3x(x+1)^3/2 - integral of 2/3(x+1)^3/2
=2/3x(x+1)^3/2- 4/15(x+1)^5/2 + c


I agree with your answer, and so does Wolfram.
You can simplify it a little to get the result that Wolfram gives.
Reply 4
Original post by joostan
I agree with your answer, and so does Wolfram.
You can simplify it a little to get the result that Wolfram gives.

Ok, the simplification is the bit I don't get then, how can it be simplified to give the answer on Wolfram?
Reply 5
Original post by couruthim
Ok, the simplification is the bit I don't get then, how can it be simplified to give the answer on Wolfram?


Pull out a factor of: 215(x+1)32\dfrac{2}{15}(x+1)^{\frac{3}{2}}.
Then simplify what remains in the usual way. It's a linear term so it's reasonably easy to rearrange into the desired form.

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