If $x = 3 + i$, then $x^{3} - 3x^{2} - 8x + 15$ is equal to

Question

Dr. Abubacker · Accepted Answer

(b)
Given, $x = 3 + i$ …(i)
Now, $x^{3} - 3x^{2} - 8x + 15$
$= (3 + i)^{3} - 3(3 + i)^{2} - 8(3 + i) + 15$
$= \left( 27 + i^{3} + 27i + 9i^{2} \right) - 3\left( 9 + i^{2} + 6i \right) - 24 - 8i + 15$
$= - 15$

Q. If $x = 3 + i$, then $x^{3} - 3x^{2} - 8x + 15$ is equal to

Explanation

Reviewed by Dr. Abubacker

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