Question:
$x^{2}+1=0$
Solution:
Given: $x^{2}+1=0$
$x^{2}+1=0$
$\Rightarrow x^{2}-1 i^{2}=0$
$\Rightarrow(x+i)(x-i)=0$ $\left[\left(a^{2}-b^{2}\right)=(a+b)(a-b)\right]$
$\Rightarrow(x+i)=0$ or $(x-i)=0$
$\Rightarrow x=-i$ or $x=i$
Hence, the roots of the equation are $i$ and $-i$.