What is the substitution rule for solving integrals with a radical expression?

[jkeatin]

Homework Statement

as 0 goes to a \int \sqrt x_{a^2-x^2} \ {dx}

Homework Equations

Substitution Rule

The Attempt at a Solution

I need help starting it, i don't understand at all

 

[Dick]

You could try a trig substitution. Does anything come to mind?

 

[jkeatin]

sorry how do i put an x before the square root
its supposed to be there

 

[Dick]

If you get into tex problems then just say it in words, i.e. integral from 0 to a of x*sqrt(a^2-x^2)dx. Is that what you mean? In that case try the even simpler substitution of u=a^2-x^2.

 

[Dick]

Is this it?
<br /> \int_0^a x \sqrt{a^2-x^2} \ {dx} <br />

 

[jkeatin]

yeah thanks

 

[HallsofIvy]

With that x dx, there is a very simple susbstitution.