Question

# (-3i)(10i)

$$\displaystyle{\left(-{3}{i}\right)}{\left({10}{i}\right)}$$

2020-11-09

We are given:
$$(−3i)(10i)$$
Multiply the numbers as usual and the imaginary unit by adding the exponents:
$$=-30i2$$
Recall that $$i=\sqrt{-1}\ so\ i2=-1$$
$$=-30(-1)$$
$$=30$$