(1+x)m=1+xe m2+4 2! mm-)-m-n+1)x"+o(x") n! (mgN) 1 =1+x+x2+…+x"+0(x")00 1-x+ − + = + + 2 2! ( 1) (1 ) 1 x m m x mx m ( ) ! ( 1) ( 1) n n x o x n m m m n + − − + +  1 ( ) 1 1 2 n n x x x o x x = + + + + + −  (m N)