The area of a rectangular deck can be modeled by f (x) = 2x3 + 30x2 6x 90. If x + 15 represents the width, which expression represents the length?

2x^2 21

2x^2 6

2x^2 + 9

2x^2 + 45,

If the area is 2x^3+30x^2+6x+90 and we know the width is x + 15, we can divide to find the length since area is length times width. x goes into 2x^3 a 2x^2 number of times. Multiply 2x^2 through by the x+15 dimension and we get 2x^3 + 30x^2. Subtract from the initial dividend and we are left with the 6x+90 portion. x+15 goes into this 6 times. This means the final solution is 2x^2+6.