Pre-Algebra Examples

$64 - 81 z^{2}$

Step 1

Rewrite $64$ as $8^{2}$ .

$8^{2} - 81 z^{2}$

Step 2

Rewrite $81 z^{2}$ as ${(9 z)}^{2}$ .

$8^{2} - {(9 z)}^{2}$

Step 3

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 8$ and $b = 9 z$ .

$(8 + 9 z) (8 - (9 z))$

Step 4

Multiply $9$ by $- 1$ .

$(8 + 9 z) (8 - 9 z)$