# Another factoring problem

• March 24th 2008, 03:35 AM
mt_lapin
Another factoring problem
$75r^2-27y^2$

What do I need to know to factor this...any helpful hints?
• March 24th 2008, 04:52 AM
mr fantastic
Quote:

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.

$=3([5r]^2 - [3y]^2)$.
• March 24th 2008, 05:14 AM
james_bond
So the answer is: $3 (5 r - 3 y) (5 r + 3 y)$.