The area of a rectangle is 56 cm. the length is 2 cm more than x and the width is 5 cm less than twice x. solve for x. round to the nearest whole number.

Area = L * W
Area = (x + 2)(2x - 5) = 56
x^2 +4x - 5x - 10 = 56
x^2 - x - 10 = 56
x^2 - x - 66 This does not factor nicely

You have to use the quadratic formula.
a = 1
b = - 1
c = - 66

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

x = 1 + /- sqrt(1^2 - 4(1)(-66)
     
                        2(1)

 = 1 +/- sqrt (265)
   
            2

= 17.279/2

= 8.639 which rounds to 9