Solve x^2 + x – 2 = 0. - Vidyadip

MCQ

Solve $x^2 + x – 2 = 0$.

A
$\frac{-1\pm\text{i}\sqrt{7}}{2}$
✓
$\frac{1\pm\text{i}\sqrt{7}}{2}$
C
$\frac{1\pm\sqrt{7}}{2}$
D
$\frac{1\pm\sqrt{7}}{2}$

✓

Answer

Correct option: B.

$\frac{1\pm\text{i}\sqrt{7}}{2}$

$\text{x}^2+\text{x}-2=0$
$\Rightarrow\text{x}^2-\text{x}+2=0$
$\text{D} =(-1)^2-4\times1\times2=1-8=-7\leq0$
Since $\text{D}\leq0,$ imaginary roots are there.
$\Rightarrow\text{x}=\frac{1\pm\sqrt{\text{D}}}{2.1}=\frac{1\pm\text{i}\sqrt{\text{D}}}{2.1}$

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