Which of the following equations will produce the graph shown below? A. x^2/20+y^2/20=1
B.20x^2-20y^2=400
C.6x^2+6y^2=144
D. x^2+y^2=16

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6