Question

Which is the product of the following numbers?

−4 (−3 + 9i )( 5 − 6i )

Answer 1

expand (- 3 + 9i )(5 - 6i ) using the FOIL method

= - 4 (- 15 + 18i + 45i - 54i² ) → i² = (√- 1 )² = - 1

= - 4 (- 15 +63i + 54 )

= - 4 (39 + 63i ) ( distribute by - 4 )

= - 156 - 252i ← in standard form