If the question was what solutions does the equation x^2 - 1 = 0 have? Then you know x^2 - 1 = (x - 1)(x + 1) = 0 so in that case you would have 2 real i.e. x = 1 and -1 But with x^2 + 1 = 0 a similar factorisation would be x^2 + 1 = (x - i)(x + i) = 0 Multiply that ...