Question

How do you simplify `3i(5-4i)`?

Answer 1

The result is `12+15i`

Explanation:

To simplify this expression you have to multiply each term in brackets: `5` and `-4i` by `3i` remembering that `i*i=-1`

`3i(5-4i)=3i*5-3i*4i=15i-12i^2=15i-12*(-1)=15i+12=12+15i`