Question

1-x+y\x=1- x-y\x+y=1\x+y+1\x-y=2\y-x-1\x-y=a\a-b-a+b\a-b=a\a-b-a+b\b-a=a\a-b+a+b\2a-2b=a\a-b+ab\(a-b)во 2 степени=a\a-b-a-b\a=