math

posted by Andrea

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

  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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