Question

How do you multiply `(-3+5i)(-5+7i)`?

Answer 1

`(-3+5i)(-5+7i) = -20-46i`

Explanation:

Multiplying out the brackets term by term gives:

`(-3+5i)(-5+7i)`
`\ \ \ \ \ = (-3)(-5) + (-3)(7i) + (5i)(-5)+(5i)(7i)`
`\ \ \ \ \ = 15-21i-25i+35i^2`
`\ \ \ \ \ = 15-46i+35i^2`
`\ \ \ \ \ = 15-46i-35 " " (because i^2=-1)`
`\ \ \ \ \ = -20-46i`