# Math Help - Another factoring problem

1. ## Another factoring problem

$75r^2-27y^2$

What do I need to know to factor this...any helpful hints?

2. Originally Posted by mt_lapin
$75r^2-27y^2$

What do I need to know to factor this...any helpful hints?
Helpful hint: Always look for a common factor.

$=3([5r]^2 - [3y]^2)$.

3. So the answer is: $3 (5 r - 3 y) (5 r + 3 y)$.