When integrating a function over two intervals where the upper bound of the first is the same as the first, the integrands can be combined. Integrands can also be split into two intervals that hold the same conditions.
If the upper and lower bound are the same, the area is 0.
If an interval is backwards, the area is the opposite sign.
Constants, such as coefficients, can be distributed out of the integrand and multiplied afterwards.
The integral of a sum can be split up into two integrands and added together
To find the total area, use the absolute value of the integrand.