+图钭学技术大荸数学系 University of Science and Technology of china DEPARTMENT OF MATHEMATICS 向后差商 f(x0) h 0 h 0数 学 系 University of Science and Technology of China DEPARTMENT OF MATHEMATICS h f x f x h f x ( ) ( ) '( ) 0 0 0 − −  向后差商 x0 -h x0