Simplify -9i*(6i+8)

$- 9 i \cdot (6 i + 8)$

Apply the distributive property.

$- 9 i (6 i) - 9 i \cdot 8$

Multiply $- 9 i (6 i)$ .

Multiply $6$ by $- 9$ .

$- 54 i i - 9 i \cdot 8$

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

$- 54 (i^{1} i) - 9 i \cdot 8$

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

$- 54 (i^{1} i^{1}) - 9 i \cdot 8$

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

$- 54 i^{1 + 1} - 9 i \cdot 8$

Add $1$ and $1$ .

$- 54 i^{2} - 9 i \cdot 8$

Multiply $8$ by $- 9$ .

$- 54 i^{2} - 72 i$

Simplify each term.

Rewrite $i^{2}$ as $- 1$ .

$- 54 \cdot - 1 - 72 i$

Multiply $- 54$ by $- 1$ .

$54 - 72 i$