Question

If $a\pm ib$ are roots of the equation $x^2+ax+b$, then (where $i=\sqrt{-1}$)

• A. $a>0$
• B. $a<0$
• C. $a=0$
• D. none of these

Answer 1

Answer: (C)

$a=0$

Sum of roots $=(a+in)+(a-ib)=2a$

But as per equation sum of roots $=-a$

$\therefore 2a=-a$

$\Rightarrow 3a=0$

$\therefore a=0$