Set each factor equal to 0 and solve for x
x+5 = 0 leads to x = -5
x+5i = 0 leads to x = -5i
x-5i = 0 leads to x = 5i
The three roots are: -5, -5i, 5i
Side note: it is not possible to order complex numbers in the form a+bi where 'b' is nonzero. Only purely real numbers can be ordered.
