Simplify 5i*(4i)

$5 i \cdot (4 i)$

Step 1

Multiply $5 i (4 i)$ .

Multiply $4$ by $5$ .

$20 i i$

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

$20 (i^{1} i)$

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

$20 (i^{1} i^{1})$

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

$20 i^{1 + 1}$

Add $1$ and $1$ .

$20 i^{2}$

Step 2

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

$20 \cdot - 1$

Step 3

Multiply $20$ by $- 1$ .

$- 20$