+       X - 1X - 1 X - X X + 1     = X - 1X - X ( X - 1)1

Câu 1: a) M = x 1 1 2 - : +       x - 1x - 1 x - x x + 1     = ^{x - 1x -} x ( x - 1)^{1 :}



x - 1

 

^{x - 1}x + 1

 

⁺ x - 1

 

² x +1



       : = . = x - 1

  

x + 1

   

x - 1

 

^{x - 1}

 

^{x + 1}



x + 1x x - 1 x - 1 x +1 x x - 1= x - 1x .b) M > 0  x - 1 > 0 (vì x > 0 nên x > 0)  x > 1. (thoả mãn)