Thực hiện phép tính: a^2-b^2-2a+b/a-2+2b-ab+a/b-1

a2−b2−2a+ba−2+2b−ab+ab−1=a2−b2−2a+ba−21−b+−a1−b=a2−b2−2a+b−aa−2a−21−b=−b2+ba−21−b=ba−2