Simplify (3b+7)(3b-7)

$(3 b + 7) (3 b - 7)$

Step 1

Expand $(3 b + 7) (3 b - 7)$ using the FOIL Method.

Apply the distributive property.

$3 b (3 b - 7) + 7 (3 b - 7)$

Apply the distributive property.

$3 b (3 b) + 3 b \cdot - 7 + 7 (3 b - 7)$

Apply the distributive property.

$3 b (3 b) + 3 b \cdot - 7 + 7 (3 b) + 7 \cdot - 7$

Step 2

Simplify and combine like terms.

Simplify each term.

Rewrite using the commutative property of multiplication.

$3 \cdot 3 b \cdot b + 3 b \cdot - 7 + 7 (3 b) + 7 \cdot - 7$

Multiply $b$ by $b$ by adding the exponents.

Move $b$ .

$3 \cdot 3 (b \cdot b) + 3 b \cdot - 7 + 7 (3 b) + 7 \cdot - 7$

Multiply $b$ by $b$ .

$3 \cdot 3 b^{2} + 3 b \cdot - 7 + 7 (3 b) + 7 \cdot - 7$

Multiply $3$ by $3$ .

$9 b^{2} + 3 b \cdot - 7 + 7 (3 b) + 7 \cdot - 7$

Multiply $- 7$ by $3$ .

$9 b^{2} - 21 b + 7 (3 b) + 7 \cdot - 7$

Multiply $3$ by $7$ .

$9 b^{2} - 21 b + 21 b + 7 \cdot - 7$

Multiply $7$ by $- 7$ .

$9 b^{2} - 21 b + 21 b - 49$

Add $- 21 b$ and $21 b$ .

$9 b^{2} + 0 - 49$

Add $9 b^{2}$ and $0$ .

$9 b^{2} - 49$