Question

Simplify the expression

Answer 1

Notice that we have a difference of squares in the numerator of our expression. In the denominator we have a quadratic expression of the form
`ax^2+bx+c`. So we can factor both numerator and denominator and cancel common terms:

`(w^2-9)/(w^2-4w-21)= (w^2-3^2)/((w+3)(w-7)) = ((w+3)(w-3))/((w+3)(w-7))= (w-3)/(w-7)`

We can conclude that the correct answer is the fourth one:
`(w-3)/(w-7)`