Question

How do you simplify `\frac { b ^ { 2} - 25} { 4b + 20}`?

Answer 1

`(b^2-25)/(4b+20)=(b-5)/4`

Explanation:

`(b^2-25)/(4b+20)=((b+5)(b-5))/(4(b+5)`

The denominator is easily factorized; the numerator must be recognized as the difference between 2 squares, those of `b` and `5`.

And thus `(b^2-25)/(4b+20)==(cancel((b+5))(b-5))/(4cancel((b+5))`

`=` `(b-5)/4`