Hoặc
Tính:
a) 1−xx+x2−1:x−1x;
a, 1−xx+x2−1:x−1x
=1−xx+xx2−1x:x−1x
=−x−1+xx+1x−1x.xx−1
=x−1−1+xx+1x.xx−1
=x−1−1+x2+x.xx.x−1
= x2 + 1 – 1;