Simplify 3(4x^2+x)-(3x^2+3x-1)

$3 (4 x^{2} + x) - (3 x^{2} + 3 x - 1)$

Step 1

Simplify each term.

Apply the distributive property.

$3 (4 x^{2}) + 3 x - (3 x^{2} + 3 x - 1)$

Multiply $4$ by $3$ .

$12 x^{2} + 3 x - (3 x^{2} + 3 x - 1)$

Apply the distributive property.

$12 x^{2} + 3 x - (3 x^{2}) - (3 x) - - 1$

Simplify.

Multiply $3$ by $- 1$ .

$12 x^{2} + 3 x - 3 x^{2} - (3 x) - - 1$

Multiply $3$ by $- 1$ .

$12 x^{2} + 3 x - 3 x^{2} - 3 x - - 1$

Multiply $- 1$ by $- 1$ .

$12 x^{2} + 3 x - 3 x^{2} - 3 x + 1$

Step 2

Simplify by adding terms.

Combine the opposite terms in $12 x^{2} + 3 x - 3 x^{2} - 3 x + 1$ .

Subtract $3 x$ from $3 x$ .

$12 x^{2} - 3 x^{2} + 0 + 1$

Add $12 x^{2} - 3 x^{2}$ and $0$ .

$12 x^{2} - 3 x^{2} + 1$

Subtract $3 x^{2}$ from $12 x^{2}$ .

$9 x^{2} + 1$