Q. 22

Find the real value of a for which 3i3 – 3ai2 + (1 – a) i + 5 is real.

Answer :

a = 2

Explanation


Z is a purely real, it means Im (z) = 0


Z = 3i3-3ai2+ (1-a) i+5


= -3i+3a+ (1-a) i+5


= (3a+5)+i(-3+1-a)


= (3a+5)+i(-2-a)


Re(z) = 3a+5 , Im(z) = (-2-a)


Z is a real so, Im (z) = 0


-2-a = 0


a = -2


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Polar & Euler Form of Complex Numbers on Argand PlanePolar & Euler Form of Complex Numbers on Argand PlanePolar & Euler Form of Complex Numbers on Argand Plane32 mins
Practice session | Argument of complex numbersPractice session | Argument of complex numbersPractice session | Argument of complex numbers61 mins
Interactive Quiz Time - Polar & Euler Form of complex numberInteractive Quiz Time - Polar & Euler Form of complex numberInteractive Quiz Time - Polar & Euler Form of complex number58 mins
Modulus & Conjugate of Complex Number | Ready for a Quiz?Modulus & Conjugate of Complex Number | Ready for a Quiz?Modulus & Conjugate of Complex Number | Ready for a Quiz?48 mins
Questions on Modulus & Conjugate of Complex NumberQuestions on Modulus & Conjugate of Complex NumberQuestions on Modulus & Conjugate of Complex Number62 mins
Special Quiz on Argument of complex numbersSpecial Quiz on Argument of complex numbersSpecial Quiz on Argument of complex numbers56 mins
Polar & Euler Form of Complex Number on Argand PlanePolar & Euler Form of Complex Number on Argand PlanePolar & Euler Form of Complex Number on Argand Plane58 mins
Questions Based on Polar & Euler Form of Complex NumberQuestions Based on Polar & Euler Form of Complex NumberQuestions Based on Polar & Euler Form of Complex Number63 mins
Get in the world of Complex NumbersGet in the world of Complex NumbersGet in the world of Complex Numbers55 mins
Discussion | Miscellaneous Exercise | NCERT Chapter 5| Complex NumbersDiscussion | Miscellaneous Exercise | NCERT Chapter 5| Complex NumbersDiscussion | Miscellaneous Exercise | NCERT Chapter 5| Complex Numbers47 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses