Simplify (a-3)(a+3)

$(a - 3) (a + 3)$

Step 1

Expand $(a - 3) (a + 3)$ using the FOIL Method.

Apply the distributive property.

$a (a + 3) - 3 (a + 3)$

Apply the distributive property.

$a \cdot a + a \cdot 3 - 3 (a + 3)$

Apply the distributive property.

$a \cdot a + a \cdot 3 - 3 a - 3 \cdot 3$

Step 2

Simplify terms.

Combine the opposite terms in $a \cdot a + a \cdot 3 - 3 a - 3 \cdot 3$ .

Reorder the factors in the terms $a \cdot 3$ and $- 3 a$ .

$a \cdot a + 3 a - 3 a - 3 \cdot 3$

Subtract $3 a$ from $3 a$ .

$a \cdot a + 0 - 3 \cdot 3$

Add $a \cdot a$ and $0$ .

$a \cdot a - 3 \cdot 3$

Simplify each term.

Multiply $a$ by $a$ .

$a^{2} - 3 \cdot 3$

Multiply $- 3$ by $3$ .

$a^{2} - 9$