To answer complex answer, there is a given formula that: i=√-1 i²=-1
Lets say for example: (4+i)² Do the square of binomial: (4+i)(4+i) =16+4i+4i+i² Add all like terms: 16+8i+i² Then since i²=-1, substitute the value: 16+8i-1 8i+15
We didn't do the 8i to 8√-1 because remember that there shuld be no negative number in square roots, so.... there:D
