A box with an open top has a square base and four sides of e

A box with an open top has a square base and four sides of equal height. The volume of the box is 704 ft^3. The height is 3 ft greater than both the length and the width. If the surface area is 416 ft^2, what are the dimensions of the box? What is the width (and length) of the box?

Solution

Here height is 3 more than length and width

And length=width=x

Therefore height=3+x

And surface area=4x(3+x)+x²

416=12x+5x²

5x²+12x-416=0

x=8