Factor 9r^2-25

$9 r^{2} - 25$

Step 1

Rewrite $9 r^{2}$ as ${(3 r)}^{2}$ .

${(3 r)}^{2} - 25$

Step 2

Rewrite $25$ as $5^{2}$ .

${(3 r)}^{2} - 5^{2}$

Step 3

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 3 r$ and $b = 5$ .

$(3 r + 5) (3 r - 5)$