Find the real number $x$ if $(x - 2 i) (1 + i)$ is purely imaginary.

2

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Solution

The correct option is B $- 2$
$(x - 2 i) (1 + i)$
$= x + i x - 2 i - 2 i^{2}$
$= (x + 2) - i (x - 2)$ is purely imaginary if (x+2)=0
$∴ x = - 2$

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