Simplify a^2(8a+9)-10(8a+9)

$a^{2} (8 a + 9) - 10 (8 a + 9)$

Apply the distributive property.

$a^{2} (8 a) + a^{2} \cdot 9 - 10 (8 a + 9)$

Rewrite using the commutative property of multiplication.

$8 a^{2} a + a^{2} \cdot 9 - 10 (8 a + 9)$

Move $9$ to the left of $a^{2}$ .

$8 a^{2} a + 9 \cdot a^{2} - 10 (8 a + 9)$

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

Move $a$ .

$8 (a \cdot a^{2}) + 9 \cdot a^{2} - 10 (8 a + 9)$

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

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

$8 (a^{1} a^{2}) + 9 \cdot a^{2} - 10 (8 a + 9)$

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

$8 a^{1 + 2} + 9 \cdot a^{2} - 10 (8 a + 9)$

Add $1$ and $2$ .

$8 a^{3} + 9 \cdot a^{2} - 10 (8 a + 9)$

$8 a^{3} + 9 a^{2} - 10 (8 a + 9)$

Apply the distributive property.

$8 a^{3} + 9 a^{2} - 10 (8 a) - 10 \cdot 9$

Multiply $8$ by $- 10$ .

$8 a^{3} + 9 a^{2} - 80 a - 10 \cdot 9$

Multiply $- 10$ by $9$ .

$8 a^{3} + 9 a^{2} - 80 a - 90$