Simplify y(y+4)-y(y-3)-9y

$y (y + 4) - y (y - 3) - 9 y$

Step 1

Simplify each term.

Apply the distributive property.

$y \cdot y + y \cdot 4 - y (y - 3) - 9 y$

Multiply $y$ by $y$ .

$y^{2} + y \cdot 4 - y (y - 3) - 9 y$

Move $4$ to the left of $y$ .

$y^{2} + 4 \cdot y - y (y - 3) - 9 y$

Apply the distributive property.

$y^{2} + 4 y - y \cdot y - y \cdot - 3 - 9 y$

Multiply $y$ by $y$ by adding the exponents.

Move $y$ .

$y^{2} + 4 y - (y \cdot y) - y \cdot - 3 - 9 y$

Multiply $y$ by $y$ .

$y^{2} + 4 y - y^{2} - y \cdot - 3 - 9 y$

Multiply $- 3$ by $- 1$ .

$y^{2} + 4 y - y^{2} + 3 y - 9 y$

Step 2

Simplify by adding terms.

Combine the opposite terms in $y^{2} + 4 y - y^{2} + 3 y - 9 y$ .

Subtract $y^{2}$ from $y^{2}$ .

$4 y + 0 + 3 y - 9 y$

Add $4 y$ and $0$ .

$4 y + 3 y - 9 y$

Add $4 y$ and $3 y$ .

$7 y - 9 y$

Subtract $9 y$ from $7 y$ .

$- 2 y$