4-1.Complex numbers
easy

Solve the equation $x^{2}+3=0$

A

$\pm \sqrt{3} i$

B

$\pm \sqrt{3} i$

C

$\pm \sqrt{3} i$

D

$\pm \sqrt{3} i$

Solution

The given quadratic equation is $x^{2}+3=0$

On comparing the given equation with $a x^{2}+b x+c=0$

We obtain $a=1, b=0,$ and $c=3$

Therefore, the discriminant of the given equation is

$D=b^{2}-4 a c=0^{2}-4 \times 1 \times 3=-12$

Therefore, the required solutions are

$=\frac{-b \pm \sqrt{D}}{2 a}=\frac{\pm \sqrt{-12}}{2 \times 1}=\frac{\pm \sqrt{12} i}{2}$     $[\sqrt{1}=i]$

$=\frac{\pm 2 \sqrt{3} i}{2}=\pm \sqrt{3} i$

Standard 11
Mathematics

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