Factor by Grouping 16x^4-81

$16 x^{4} - 81$

Step 1

Rewrite $16 x^{4}$ as ${(4 x^{2})}^{2}$ .

${(4 x^{2})}^{2} - 81$

Step 2

Rewrite $81$ as $9^{2}$ .

${(4 x^{2})}^{2} - 9^{2}$

Step 3

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 4 x^{2}$ and $b = 9$ .

$(4 x^{2} + 9) (4 x^{2} - 9)$

Step 4

Simplify.

Rewrite $4 x^{2}$ as ${(2 x)}^{2}$ .

$(4 x^{2} + 9) ({(2 x)}^{2} - 9)$

Rewrite $9$ as $3^{2}$ .

$(4 x^{2} + 9) ({(2 x)}^{2} - 3^{2})$

Factor.

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

$(4 x^{2} + 9) ((2 x + 3) (2 x - 3))$

Remove unnecessary parentheses.

$(4 x^{2} + 9) (2 x + 3) (2 x - 3)$

Factor by Grouping 16x^4-81

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