If we know that the absolute value of the square of (x minus 1) plus 2, x minus y plus a is equal to 0, and Y is negative, then the value range of C is 0

If we know that the absolute value of the square of (x minus 1) plus 2, x minus y plus a is equal to 0, and Y is negative, then the value range of C is 0

The absolute value of the square of (x minus 1) plus 2 x minus y plus a is equal to 0
So X-1 = 0
2x-y+a=0
So x = 1
Y is negative
Then y = 2x-a = 2-A2