It is known that the quadratic equation AX2 + BX + C = 0 with respect to X. when the coefficients a, B and C satisfy a-2b + 4C = 0, there is a root which can be determined. The root is: - (excluding a, B and C)

It is known that the quadratic equation AX2 + BX + C = 0 with respect to X. when the coefficients a, B and C satisfy a-2b + 4C = 0, there is a root which can be determined. The root is: - (excluding a, B and C)

1/4*a-1/2*b+c=0,x=-1/2