Definite integral with x^2+c in the denominator

[Hypatio]

Homework Statement

Homework Equations

solve the definite integral

$$\int_{2.6}^{5.5} \frac{1}{x^2+9}dx$$

The Attempt at a Solution

ln(5.5^2+9)-ln(2.6^2+9) doesn't seem correct

 

[king vitamin]

Can you show your steps in getting that solution? What did you get for the antiderivative of the integrand?

 

[Dick]

Homework Statement

Homework Equations

solve the definite integral

$$\int_{2.6}^{5.5} \frac{1}{x^2+9}dx$$

The Attempt at a Solution

ln(5.5^2+9)-ln(2.6^2+9) doesn't seem correct

If you take the derivative of log(x^2+9) you will not get 1/(x^2+9) (at least if you don't forget the chain rule). You need a trig substitution to do that integral.