If x = 3i is a zero of P(x ) = x4 - 2x3 + x2 - 18x - 72 , then another zero must be x = 2?
- Dr DLv 71 decade agoFavorite Answer
x = 3i works.
x = 2 does not work.
There will also be zero at x = -3i
P can be factorized as follows:
P(x) = (x^2 + 9) * (x^2 - 2x - 8)
= (x^2 + 9) * (x-4)*(x+2)
The other roots are x = -2 and +4
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