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If $z = a + ib$ is non-zero, its multiplicative inverse $z^{-1}$ is:
A$\dfrac{a - ib}{a^2 + b^2}$
B$\dfrac{a + ib}{a^2 + b^2}$
C$a - ib$
D$\dfrac{1}{a} + \dfrac{1}{ib}$
Answer & Solution
Correct answer: A. $\dfrac{a - ib}{a^2 + b^2}$
z⁻¹ = conj(z)/|z|² = (a − ib)/(a² + b²).
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