The dimensions of a rectangle are x+4 and 3x-1. Write an expression to represent the area of the rectangle.

9x^4 - 6x^3 + 97x2 - 88x + 16

Step-by-step explanation:

so (x + 4) (x + 4) = x^2 + 8x + 16 is the total length of the rectangle, and

(3x - 1) (3x - 1) = 9x^2 - 6x + 1, if you multiply each other, because Area = length times width, then you get the area.

(9x^2 - 6x + 1) (x^2 + 8x + 16) = 9x^4 + 72x^2 + 144x^2 - 6x^3 - 48x^2 - 96x + x^2 + 8x + 16, and then you add them all together = 9x^4 - 6x^3 + 98x^2 - 96x + 8x + 16 = 9x^4 - 6x^3 + 97x2 - 88x + 16