Simplify -3i(-5i)

$- 3 i (- 5 i)$

Step 1

Multiply $- 3 i (- 5 i)$ .

Multiply $- 5$ by $- 3$ .

$15 i i$

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

$15 (i^{1} i)$

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

$15 (i^{1} i^{1})$

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

$15 i^{1 + 1}$

Add $1$ and $1$ .

$15 i^{2}$

Step 2

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

$15 \cdot - 1$

Step 3

Multiply $15$ by $- 1$ .

$- 15$