merci de bien vouloir m aider !!

E=x²-2x-x+2-x²+3x
  =2
99 999 x 99 998 - 100 000 x 99 997=99 999 x 99 998 - (99 999 - 1) x 99 997
=99 999 x 99 998 - 99 999 x 99 997 -99 997
=99 999(99 998 - 99 997) -99 997
=99 999 x 1 -99 997
=2