1.

If `z = -5 + 3i`, find the value of `(z^(4)+9z^(3)+26z^(2)-14z + 8)`.

Answer» We have
`z = -5 + 3i rArr (z + 5) = 3i rArr (z+5)^(2) = 9i^(2) rArr z^(2) + 10z + 34 = 0." "...(i)`
Now, `z^(4) + 9z^(3) + 26z^(2) - 14z + 8`
`= z^(2)(z^(2) + 10z + 34) -z(z^(2) + 10z + 34) + 2(z^(2) + 10z + 34) - 60" "["using (i)"]`
Hence, the value of `z^(4) + 9z^(3) + 26z^(2) - 14z + 8` is -60.


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