Simplify (7x+9)(7x-9)

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

Step 1

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

Apply the distributive property.

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

Apply the distributive property.

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

Apply the distributive property.

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

Step 2

Simplify and combine like terms.

Simplify each term.

Rewrite using the commutative property of multiplication.

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

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

Move $x$ .

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

Multiply $x$ by $x$ .

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

Multiply $7$ by $7$ .

$49 x^{2} + 7 x \cdot - 9 + 9 (7 x) + 9 \cdot - 9$

Multiply $- 9$ by $7$ .

$49 x^{2} - 63 x + 9 (7 x) + 9 \cdot - 9$

Multiply $7$ by $9$ .

$49 x^{2} - 63 x + 63 x + 9 \cdot - 9$

Multiply $9$ by $- 9$ .

$49 x^{2} - 63 x + 63 x - 81$

Add $- 63 x$ and $63 x$ .

$49 x^{2} + 0 - 81$

Add $49 x^{2}$ and $0$ .

$49 x^{2} - 81$