Question

the length of a rectangular floor is 5 feet less than twice its width the area of the floor is 150 square feet what is width of the room?

Answer 1

Think of it like an equation: (w = width, l = length)

5 = 2w - l
lw = 150

l = 150 / w
5 = 2w - (150/w)
5w = 2w^2 - 150
2w^2 - 5w - 150 = 0            <- you can see this is now a quadratic equation

w = (-b^2 + sqrt(b^2 - 4ac))/2a
w = 10

width = 10