Q138 / 200 · TS EAMCET 2002 · Mathematics

If $1-i$ is a root of the equation $x^2+a x+b=0$ then $b$ is equal to

  • A
    $1$
  • B
    $-1$
  • C
    $-2$
  • Correct answer
    D
    $2$

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 $=b$ $$ \begin{array}{rlrl} \Rightarrow & & (1+i)(1-i) & =b \\ \Rightarrow & 1+1 & =b \Rightarrow b=2 \end{array} $$

Hence, the correct answer is option: 'D'.

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