Q. Let $z = \frac{11 - 3i}{1 + i}$. If $\alpha$ is a real number such that $z - i\alpha$ is real, then the value of $\alpha$ is

A) 4
B) -4
C) 7
D) -7
Explanation

(d)
Given,
$z = \frac{11 - 3i}{1 + i} \times \frac{1 - i}{1 - i} = \frac{8 - 14i}{2} = 4 - 7i$
Since, $z = i\alpha$ is real, therefore $4 - 7i - i\alpha$ is real, if $\alpha = - 7$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.