MCQ
Solve – x2 + x – 2 = 0.
- A$\frac{-1\pm\text{i}\sqrt{7}}{2}$
- B$\frac{1\pm\text{i}\sqrt{7}}{2}$
- C$\frac{1\pm\sqrt{7}}{2}$
- D$\frac{1\pm\sqrt{7}}{2}$
✓
Answer
- $\frac{1\pm\text{i}\sqrt{7}}{2}$
Solution:
$\text{x}^2+\text{x}-2=0$
$\Rightarrow\text{x}^2-\text{x}+2=0$
$\text{D} =(-1)^2-4\times1\times2=1-8=-7\leq0$
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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