Because the values in the root sign are all greater than or equal to 0.

x- 1 & gt； =0

1-x & gt； =0

When the two formulas are combined, x= 1

So y=-4.

the second question

The root sign is greater than or equal to 0, and the absolute value is greater than or equal to 0.

Because the right side of the equal sign is equal to 0, only the root sign =0 and the absolute value =0.

X= 1 or-1, Y=- 1.