Imaginary numbers never appeared in linear equations, but they began to crop up in quadratic ones. Consider the equation x2 + 1=0. No number seems to solve the equation; plugging in –1, 3, –750, 235.23, or any other positive or negative number you could think of doesn’t yield the correct answer. The expression simply will not split. Worse yet, when you try to apply the quadratic equation, you get two silly-sounding answers:
