ABCD is a rectangle with sides of lengths x centimetres and (x − 2) centimetres.If the area of ABCD is less than 15 cm^2 , determine the range of possible values of x.

First you interpret the given information and create an equation based on the question. x(x-2)<15. Then you express that equation in standard quadratic form: x^2-2x-15<0. Then you have to not forget that x cannot be smaller than 2, because a side of a rectangle cannot be negative. Then you factorise the equation: (x-5)(x+3)<0. And finally you come to the conclusion that the state range is 2<x<5.