Answer:
Option B.
Step-by-step explanation:
The given curve is
We need to find the area of the largest rectangle with lower base on the x-axis and upper vertices on the curve .
Let the vertex in quadrant I be (x,y), then the vertex in quadrant II is (-x,y) .
Length of the rectangle = 2x
Width of the rectangle = y
Area of a rectangle is
Substitute the value of y from the given equation.
.... (1)
Differentiate with respect to x.
Equate , to find the critical points.
Divide both sides by 6.
The value of x can not be negative because side length can not be negative.
Substitute x=3 in equation (1).
The area of the largest rectangle is 108 square units.
Therefore, the correct option is B.