Is 2+i a solution of z^2-4z+5=0? Please help!!!!!!! :(

Answer 1

z^2 - 4z + 5 = 0

(Note that the square of i is equal to -1)

(2 + i)^2 - 4(2 + i) + 5
= 4 + (i^2) + 4i - 8 - 4i + 5
= 4 - 1 - 8 + 5
= 9 - 9
= 0

Hence, yes, it is a solution.