Question

If $(3+i)$ is a root of the equation $x^2+ax+b=0$ then $a$ is

• A. $3$
• B. $-3$
• C. $6$
• D. $-6$

Answer 1

Answer: (D)

$-6$

Given $(3+i)$ is a root of the equation $x^2+ax+b=0$.

Since $a,b,c$ are real numbers then also $(3-i)$ will be the other root of the given equation.

Now, sum of the roots is $=6$ and is equal to $-a$.

So,

$-a=6$

or, $a=-6$.