# math

posted by Andrea

1. Arora

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.

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