# Homework Help: May be i dont see anything

1. Jan 18, 2010

### sania16

1. The problem statement, all variables and given/known data
$$\int1/\sqrt{(4+9x^2)^3}dx$$

3. The attempt at a solution:

i think i do all options that i now, but i cannt to make a solution of this, (the way)? may be anybody can help me,

2. Jan 18, 2010

### pellman

You can get the answer here: http://integrals.wolfram.com/index.jsp

Enter 1/(Sqrt((4+9*x*x)^3))

Maybe once you have the answer it will give you some ideas about how to solve it.

If you still need help, come back and let us know.

3. Jan 18, 2010

### sania16

eeeeeeeeemmmh thnks, the answer i know, and in others sites,i gave the same answer,

but i want to see the way.... :(((((((((((

4. Jan 18, 2010

### tiny-tim

Welcome to PF!

Hi sania16! Welcome to PF!

(have a square-root: √ and an integral: ∫ and try using the X2 tag just above the Reply box )
Quite right!

Hint: for √(a ± bx2), always try a trig substitution first.

5. Jan 18, 2010

### sania16

yes you right !!!! thank you.

i change 3x=2tg(t), and everything being cool!!!

thanks to all of you!!!

p.s: how much time i spend on this.... :(