# Thread: Evaluate the definite integral of x^(-1)

1. ## Evaluate the definite integral of x^(-1)

I'm just starting calc II and I didn't manage to see a lot of examples, but from the basic information I have got so far I'm confused about this one:

$\int_{-6}^{-3} (x^{-1} + 4x)$ and by evaluating it I get $(ln|x| + 2x^{2})$ that I need to evaluate from -3 to -6 , how do I evaluate the ln|x| for negative numbers, or there is a trick I don't see...

thank you,

2. ## Re: Evaluate the definite integral of x^(-1)

The key here is that the argument of the logarithm is $|x|$, not just $x$.

3. ## Re: Evaluate the definite integral of x^(-1)

Originally Posted by FelixFelicis28
The key here is that the argument of the logarithm is $|x|$, not just $x$.
so I can do in this way $ln|x| = ln|-3| = ln3$ ...

yes