Evaluate
`int sqrt(9x^2+4) dx`

Explanation

To evaluate the integral \( \int \sqrt{9x^2 + 4} \, dx \), we can follow these steps:

### Step 1: Rewrite the expression under the square root
We can express \( 9x^2 + 4 \) in a more recognizable form:
\[ 9x^2 + 4 = (3x)^2 + 2^2 \]
This suggests that we can use a trigonometric substitution or a standard integral formula.
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