- #1
Refraction
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Homework Statement
Looks like I'm back with another question already I need to change the order of integration for this double integral and then evaluate it, but I get to a point where I'm not sure what to do.
Homework Equations
[tex]\int^3_{0} \int^9_{y} \sqrt{x}cos(x) dx dy[/tex]
The Attempt at a Solution
With the changed order of integration it needs two integrals added together, this is what I came up with:
[tex]\int^3_{0} \int^x_{0} \sqrt{x}cos(x) dy dx + \int^9_{3} \int^3_{0} \sqrt{x}cos(x) dy dx[/tex]
And I planned to work them both out separately, but didn't get too far with the first one:
[tex]= \int^3_{0} \left[y\sqrt{x}cos(x)\right]^{x}_{0} dx[/tex]
[tex]= \int^3_{0} x\sqrt{x}cos(x) dx[/tex]
I'm not sure if I've made a mistake getting here, but it looks like I need to integrate [tex]x\sqrt{x}cos(x)[/tex] and there doesn't seem to be an easy way to do that at all.