#/***********************************************************
#    quadeq.rb -- 2次方程式
#***********************************************************/

printf("a = ");  a = gets.to_f
printf("b = ");  b = gets.to_f
printf("c = ");  c = gets.to_f
if (a != 0) 
    b /= a;  c /= a;     # $a$ で割って $x^2 + bx + c = 0$ の形にする 
    if (c != 0) 
        b /= 2;          # $x^2 + 2b'x + c = 0$ 
        d = b * b - c;   # 判別式 $D / 4$ 
        if (d > 0) 
            if (b > 0); x = -b - Math::sqrt(d)
            else;       x = -b + Math::sqrt(d); end
            printf("x = %g, %g\n", x, c / x)
        elsif (d < 0)
            printf("x = %g +- %g i\n", -b, Math::sqrt(-d))
        else
            printf("x = %g\n", -b)
        end
    else
        printf("x = %g, 0\n", -b)
    end
elsif (b != 0)
    printf("x = %g\n", -c / b)
elsif (c != 0)
   printf("解なし.\n")
else
   printf("不定.\n")
end

exit 0