Evaluate (9x+7)(9x-7)

$(9 x + 7) (9 x - 7)$

Step 1

Expand $(9 x + 7) (9 x - 7)$ using the FOIL Method.

Apply the distributive property.

$9 x (9 x - 7) + 7 (9 x - 7)$

Apply the distributive property.

$9 x (9 x) + 9 x \cdot - 7 + 7 (9 x - 7)$

Apply the distributive property.

$9 x (9 x) + 9 x \cdot - 7 + 7 (9 x) + 7 \cdot - 7$

Step 2

Simplify terms.

Combine the opposite terms in $9 x (9 x) + 9 x \cdot - 7 + 7 (9 x) + 7 \cdot - 7$ .

Reorder the factors in the terms $9 x \cdot - 7$ and $7 (9 x)$ .

$9 x (9 x) - 7 \cdot 9 x + 7 \cdot 9 x + 7 \cdot - 7$

Add $- 7 \cdot 9 x$ and $7 \cdot 9 x$ .

$9 x (9 x) + 0 + 7 \cdot - 7$

Add $9 x (9 x)$ and $0$ .

$9 x (9 x) + 7 \cdot - 7$

Simplify each term.

Rewrite using the commutative property of multiplication.

$9 \cdot 9 x \cdot x + 7 \cdot - 7$

Multiply $x$ by $x$ by adding the exponents.

Move $x$ .

$9 \cdot 9 (x \cdot x) + 7 \cdot - 7$

Multiply $x$ by $x$ .

$9 \cdot 9 x^{2} + 7 \cdot - 7$

Multiply $9$ by $9$ .

$81 x^{2} + 7 \cdot - 7$

Multiply $7$ by $- 7$ .

$81 x^{2} - 49$