Remember that the area of a rectangle is the length of the rectangle multiplied by the width of the rectangle.
In this case, we could say (where is the area of the rectangle):
Substituting the values the problem gave us for and
, we can find the formula for
in terms of
, which is:
The formula for the area of the rectangle would be A(x) = 10x³ - 20x² + 65x.