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Let z= \left ( 2a-3 \right )+i\left ( 4a+5 \right ) is a complex number which is purely imaginary, then Im(z) equals \left ( a\: \epsilon \: R \right )

 Your Option is correct !!

A.

9

B.

10

C.

11

D.

12

Answers (1)

best_answer

Given a complex number:

z= \left ( 2a-3 \right )+i\left ( 4a+5 \right )

Since it is given that the number is purely imaginary, the real part of the complex number will be zero.

So,

2a-3=0

a=\frac{3}{2}

Hence 

The imaginary part of the number :

=4a+5

=4\left (\frac{3}{2} \right )+5

=11.

Hence option (C) is correct.

Posted by

Pankaj Sanodiya

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