# Problem with math integral substitution

1. Feb 19, 2005

$$\int \frac{1}{4x+7*sqrt(x)}$$

what would be a good u substituion for this problem? i cant think of any at the moment

2. Feb 19, 2005

### Fredrik

Staff Emeritus
$$y=\sqrt x$$ is a good start.

3. Feb 19, 2005

### dextercioby

The answer is $$\frac{1}{2}\ln (4\sqrt{x}+7) +C$$

Daniel.

P.S.Sure,the integral is evaluated in $(0,+\infty)$.