Question

(6+√-64)(3-√-16) Multiply. This is urgent, please explain this to me!

Answer 1

50

Explanation:

`√(-64)` and
`√(-16)` can be expressed in complex form, with
`√(-1)` = i

`√(-64)` =
`√(64(-1))` =
`√(64)` ×
`√(-1)` = 8i

`√(-16)` =
`√(16(-1))` =
`√(16)` ×
`√(-1)` = 4i

the factors can then be expressed as

(6 + 8i)(3 - 4i) ← expand using FOIL

= 18 - 24i + 24i - 32i² [ i² = (
`√(-1)` )² = - 1 ]

= 18 - 24i + 24i + 32 ← collect like terms

= 18 + 32 + 0

= 50