Question

when finding the area between two curves, you have to integrate. and in the formula, there is f(x)-g(x).
how do you know which one is f(x) , and which one is g(x) ?

Answer 1

\[\int\limits_{a}^{b}(f(x)-g(x))dx\]
that is the formula.

Answer 2

I hope the drawing isn't too confusing. Anyway, the short answer is, when integrating in the X direction, you subtract the LOWER function from the UPPER.