Estimated area under y = 0.0x^0 + 2.0x^1
   between x = 0.0 and x = 4.0 using 4 rectangles is 12.0

Estimated area under y = 0.0x^0 + 2.0x^1
   between x = 0.0 and x = 4.0 using 8 rectangles is 14.0

Estimated area under y = 2.0x^0 + 0.0x^1 + 1.0x^2
   between x = -3.0 and x = 1.0 using 4 rectangles is 22.0