What is the height, width, and depth of the shed, in feet, if the volume is 990 ft^3?

Question

A shed in the shape of a rectangular prism measures x feet high, x + 6.5 feet wide, and is x − 4 feet deep, the

volume of the shed is given by the function v(x) = x^3 + 2.5x^2 − 26x. What is the height, width, and depth of the shed, in feet, if the volume is 990 ft^3?

Answer 1

But the equation has a rational root, x=10!!!!

1000+250-260-990=0

So now plug into the value given for the other 2 side