If $1-i$ is a root of the equation $x^2+a x+b=0$ then $b$ is equal to
If $1-i$ is a root of the equation $x^2+a x+b=0$ then $b$ is equal to
$1$
$-1$
$-2$
$2$
Solution
Since $1-i$ is a ront of the equation $x^2+9 x+b=0$ then another root will be $1+i$, also, product of roots $=b$
$
\begin{array}{rlrl}
\Rightarrow & & (1+i)(1-i) & =b \\
\Rightarrow & 1+1 & =b \Rightarrow b=2
\end{array}
$