Answer:
A = x⁵ + 13x³ - 9x² + 40x - 72
Explanation:
The formula for the area of a rectangle is length X width, or A = lw.
Substitute the equations for the sides into the formula:
A = lw
A = (x² + 8)(x³ + 5x - 9) <= use the distributive property
A = x⁵ + 5x³ -9x² + 8x³ + 40x - 72 <= collect like terms
A = x⁵ + 13x³ - 9x² + 40x - 72