定理2f(x)在点x的泰勒级数,在U(x0)内收 敛于f(x)兮在U。(x0)内lmRn(x)=0 n→00 证明必要性设(x)能展开为泰勒级数 f(x)=∑ 0(x-x0)2+Rn(x) R,()=f(x)-sm(x),. lims+()=f(x) n→0 lim R,()=limlf(x)-sm+()=0; n→00定 理 2 f (x)在 点x0的泰勒级数,在 ( ) U x0 内 收 敛 于 f (x)在 ( ) U x0 内lim ( ) = 0 → Rn x n . 证明 必要性 ( ) ( ) ! ( ) ( ) 0 0 0 ( ) x x R x i f x f x n i n i i =  − + =  ( ) ( ) ( ), Rn x = f x − sn+1 x 设f (x)能展开为泰勒级数, lim ( ) ( ) sn 1 x f x n + = →   = → lim R (x) n n lim[ ( ) ( )] f x sn 1 x n + → − = 0;