Simplify -3y(y^2-4)

$- 3 y (y^{2} - 4)$

Step 1

Apply the distributive property.

$- 3 y \cdot y^{2} - 3 y \cdot - 4$

Step 2

Multiply $y$ by $y^{2}$ by adding the exponents.

Move $y^{2}$ .

$- 3 (y^{2} y) - 3 y \cdot - 4$

Multiply $y^{2}$ by $y$ .

Raise $y$ to the power of $1$ .

$- 3 (y^{2} y^{1}) - 3 y \cdot - 4$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$- 3 y^{2 + 1} - 3 y \cdot - 4$

Add $2$ and $1$ .

$- 3 y^{3} - 3 y \cdot - 4$

Step 3

Multiply $- 4$ by $- 3$ .

$- 3 y^{3} + 12 y$