The Definite Integral

*"the integral of f(x) form a to b, with respect
to x"*

The definite integral was defined on the last worksheet as the limit of and to evaluate the definite integral we used the Fundamental Theorem of Calculus.

For ease, we let F(x) be the antiderivative where
C=0. Even if we use C, it would subtract out anyway.

**Note:** If f(x) is positive for all x in the
interval from a to b, then this definite integral is
exactly the area under the curve and above the x-axis.

To find the value of the definite integral, find
the antiderivative first (just like the indefinite
integral), then evaluate the antiderivative at the
"upper limit, b, and subtract the value of the
antiderivative at the "lower limit", a. The definite
integral is a number. The indefinite integral was
a function.

**Try it!**

Problem 1:

Problem 2: