# Homework Help: Integration with inverse trig

1. Feb 12, 2009

### crm08

1. The problem statement, all variables and given/known data

$$\int\frac{dx}{9x^{2}+1}$$

2. Relevant equations

$$\frac{d}{dx}(arctan(x))$$ = $$\frac{1}{1+x^{2}}$$

3. The attempt at a solution

The other problems in this homework set all use the substitution rule but I can't find anything that would simplify the problem, my other guess would be to pull a (1/9) out, but then that would result in having a denominator = (x^2 + (1/9)), could someone get me on the right track, I have a feeling that I'm overlooking something obvious

2. Feb 12, 2009

### rootX

Try u = 3x

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