What cases are possible when solving an equation of the form x ^ 2 = a, where x is a variable and a is some number?

When solving an equation of the form x ^ 2 = a, 3 cases are possible:

1) if a> 0, i.e. if a is a positive number, then the equation has 2 roots;

x1 = √a; x2 = – √a;

2) if a = 0, then the equation has 1 root;

x = 0;

3) if a <0, i.e. if a is a negative number, then the equation has no roots, because we cannot take the square root of a negative number.