Question

Find the area lying above the x-axis and below the parabolic curve y = 4x -x2 A. 8 B. 16 C. 10 2/3 D. 8 1/3

Answer 1

To find the area between the x-axis and the parabolic curve, take the integral of the area in which the curve is above the x-axis.
function of the graph is
y = 4x - x²
We can tell by the function (specifically -x²) that the parabola will point downward.
To find the domain in which y>0, let's find the roots (0's) of the function:
0 = 4x - x²
0 = x (4 - x) 
x = 0 or x = 4
Between x=0 and x=4, the curve is above the x-axis. To find the area of the graph, let's take the integral on this range:

First, take the antiderivative of 4x - x²:
2x² - (1/3) x³
Then, plug x=4 into the anti-derivative, and subtract the anti-derivative at x=0:
2(4)² - (1/3)(4³) - (0 - 0)
32 - 64/3
96/3 - 64/3 = 32/3 

Closest Answer is C) 10