Answers

2016-07-13T20:34:32+08:00
2x-1x+1x..............................

0
Incorrect. Check the answer or another user, cheajimmy.
2016-07-13T23:31:52+08:00
  ( x+1)(x-1)
   this expression is called difference of two squares
   it's very important, and should be remembered by heart
     the pattern is         (a+b)(a-b)  =  a² - b²
     thus
               (x + 1)(x-1)  =   x² - 1²   =  x² -1
1 5 1