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Topic: calc help
Replies: 2   Last Post: Jan 21, 2005 3:11 PM

 Messages: [ Previous | Next ]
 ticbol Posts: 116 Registered: 1/25/05
Re: calc help
Posted: Jan 21, 2005 3:07 PM

INT.[x(4 -2x^2)^(1/2)]dx

Let u = (4 -2x^2)
So, du = -4x dx
And (4 -2x^2)^(1/2) = u^(1/2)
Then,
INT.[x(4 -2x^2)^(1/2)]dx
= INT.[(4 -2x^2)^(1/2)]x dx
= INT.[(4 -2x^2)^(1/2)](-4/-4)x dx
= (-1/4) INT.[(4 -2x^2)^(1/2)](-4x dx)
= -(1/4)INT.[u^(1/2)]du
= -(1/4)[1/(3/2)*(u^(3/2))] +C
= -(1/4)(2/3)u^(3/2) +C
= -(1/6)u^(3/2) +C

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Date Subject Author
1/21/05 ticbol
1/21/05 Kevin Karplus