Simplify (7a)(3ab)-4a^2b

$(7 a) (3 a b) - 4 a^{2} b$

Step 1

Simplify each term.

Multiply $a$ by $a$ by adding the exponents.

Move $a$ .

$7 (a \cdot a) (3 b) - 4 a^{2} b$

Multiply $a$ by $a$ .

$7 a^{2} (3 b) - 4 a^{2} b$

Rewrite using the commutative property of multiplication.

$7 \cdot 3 a^{2} b - 4 a^{2} b$

Multiply $7$ by $3$ .

$21 a^{2} b - 4 a^{2} b$

Step 2

Subtract $4 a^{2} b$ from $21 a^{2} b$ .

$17 a^{2} b$