Quadratic equation in Wolfram Mathematica

Example for versions Wolfram Mathematica 8.0.4

After accepting user input we define variable y which is a quadratic equation with the given coefficients. Since x is not defined yet, it stays a variable — for example, Print[y] will output the notation of the equation c + b x + a x^2 (with c, b and a replaced with values entered by the user). Reduce calculates the values of the variables which satisfy the condition “equation value equals zero”. 

a = Input["Input a", 0];
b = Input["Input b", 0];
c = Input["Input c", 0];
y = a*x^2 + b*x + c;
Print[Reduce[y == 0]];