# Quick integration question

1. Apr 13, 2010

### vorcil

I need to figure out,

$$\int_0^h \frac{1}{2\sqrt{hx}}dx$$

If h is a constant,

how do i do this?

my book shows that I can pull out,

$$\frac{1}{2\sqrt{h}} \int \frac{1}{\sqrt{x}}dx$$

How does the 2 from $$\frac{1}{2\sqrt{hx}}$$ come out with the $$\sqrt{h}$$?

I thought I would've only been able to pull out 1/root h,

like this,

$$\frac{1}{\sqrt{h}} \int \frac{1}{2\sqrt{x}}dx$$

-

why does 2 root h get assigned constant? instead of only h

2. Apr 13, 2010

### rock.freak667

1/2 is a constant, 1/√h is a constant

it must follow that

1/2√h is constant as well.

3. Apr 13, 2010

### Staff: Mentor

The basic idea is that $\int k*f(x) dx = k*\int f(x) dx$.

The rest in your problem is just algebra.
$$\frac{1}{2\sqrt{hx}} = \frac{1}{2*\sqrt{h}\sqrt{x}} = \frac{1}{2\sqrt{h}} \frac{1}{\sqrt{x}}$$

Integration is being done with respect to x (i.e., with x as the variable), so h is just another constant in this process.

4. Apr 13, 2010

cheers