£ a b (f(x)dx) = F(a)-F(b)
1. £ -1 -2(x²dx) = 1/3 x³|-1 -2 = -1/3+8/3 = 7/3
S = 7/3
2. £ 3 0 ((-x²+4x)dx) = -1/3 x³ + 2x²|3 0 = -9+2•9 = 9
S = 9
