Question

Which expression is equivalent to 2i(5+3i)

A) 6+10i
B) -10+6i
C) 10+61
D) -6+10i

Answer 1

D

Explanation:

`2i(5 + 3i)`

`10i + 6i^(2)` (multiplying 2i by both 5 and 3i)

(here
`i` is a complex number which has a value of
`√(-1)`)

( hence
`i^(2)` becomes
`√(-1)` ×
`√(-1) = √(-1)^2 = -1`)

`10i + 6(-1)`

`10i - 6 = -6 + 10i`