logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
0 votes

The real value of $' a '$ for which $\;3i^{3}-2ai^{2}+(1-a)i+5\;$ is real is

$(a)\;-2\qquad(b)\;\pm6\qquad(c)\;\pm3\qquad(d)\;4$

Can you answer this question?
 
 

1 Answer

0 votes
Answer : $-\;2$
Explanation :
$\;3i^{3}-2ai^{2}+(1-a)i+5\; =-3i+2a+5+(1-a)i $
$=2a+5+i(-a-2)\;$, which is real
If $\;-a-2 =0\; i .e \;a=-2$
answered Apr 17, 2014 by yamini.v
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...