Simplify 9i*(-4-7i)

$9 i \cdot (- 4 - 7 i)$

Step 1

Apply the distributive property.

$9 i \cdot - 4 + 9 i (- 7 i)$

Step 2

Multiply $- 4$ by $9$ .

$- 36 i + 9 i (- 7 i)$

Step 3

Multiply $9 i (- 7 i)$ .

Multiply $- 7$ by $9$ .

$- 36 i - 63 i i$

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

$- 36 i - 63 (i^{1} i)$

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

$- 36 i - 63 (i^{1} i^{1})$

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

$- 36 i - 63 i^{1 + 1}$

Add $1$ and $1$ .

$- 36 i - 63 i^{2}$

Step 4

Simplify each term.

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

$- 36 i - 63 \cdot - 1$

Multiply $- 63$ by $- 1$ .

$- 36 i + 63$

Step 5

Reorder $- 36 i$ and $63$ .

$63 - 36 i$