If (K-4) x + (K-2) x + (K + 3) y = K + 1 is a quadratic equation with respect to XY, what is the value of K?

If (K-4) x + (K-2) x + (K + 3) y = K + 1 is a quadratic equation with respect to XY, what is the value of K?

Because (K-4) x + (K-2) x + (K + 3) y = K + 1 is a bivariate linear equation about XY, the coefficient of the quadratic term must be 0, that is, K-4 = 0, so k = ± 2, but when k = 2, the coefficient K-2 in front of x is equal to 0, so the original formula becomes a bivariate linear equation, so K ≠ 2, so k = - 2