$i$ is called an imaginary number. It's unreal, because there is no real number whose square is $-1$. It doesn't match reality. In reality, a square of any non-zero number is always positive. Or is it? Have you ever wondered why the result of multiplying a negative number with a negative number must be positive?
$(-1)^2$
$(-1)^2$
$(-1)^2$
$i$ is called an imaginary number. It's unreal, because there is no real number whose square is $-1$. It doesn't match reality. In reality, a square of any non-zero number is always positive. Or is it? Have you ever wondered why the result of multiplying a negative number with a negative number must be positive?