Thread: [SOLVED] Integration

1. [SOLVED] Integration

I am integrating by parts. I do not know what let u and v be. I am also stuck on the radical.

e^{sqre rt} 3s+9 ds

I want to let u = 3s+9 and v = e^rt x

can it be done or am i just lost?

2. $\int e^{\sqrt{3s+9}} \, ds
$

$t = \sqrt{3s+9}$

$dt = \frac{3}{2\sqrt{3s+9}} \, ds = \frac{3}{2t} \, ds$

$ds = \frac{2t}{3} \, dt$

$\int e^t \cdot \frac{2t}{3} \, dt$

$\frac{2}{3} \int t \cdot e^t \, dt$

now do parts ... let $u = t$ and $dv = e^t \, dt$

3. Why did you solve for ds?

4. because one cannot integrate a function of t w/respect to s.

5. Thank You

Thanks skeeter.