Simplify 3x(7x-4)

$3 x (7 x - 4)$

Step 1

Simplify by multiplying through.

Apply the distributive property.

$3 x (7 x) + 3 x \cdot - 4$

Simplify the expression.

Rewrite using the commutative property of multiplication.

$3 \cdot 7 x \cdot x + 3 x \cdot - 4$

Multiply $- 4$ by $3$ .

$3 \cdot 7 x \cdot x - 12 x$

Step 2

Simplify each term.

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

Move $x$ .

$3 \cdot 7 (x \cdot x) - 12 x$

Multiply $x$ by $x$ .

$3 \cdot 7 x^{2} - 12 x$

Multiply $3$ by $7$ .

$21 x^{2} - 12 x$