If ax + (A-1) Y-7 = 0 is a bivariate linear equation about X, y, then the value range of a is Writing process

If ax + (A-1) Y-7 = 0 is a bivariate linear equation about X, y, then the value range of a is Writing process

Because of the quadratic equation of two variables, a is not equal to 0 or 1. Everything else is OK