生质41.d=「dc=b-a 生质5如果在区间a,b上f(x)≥0, 则f(x)≥0.(a<b) 证f(x)≥0,…f(5)≥0,(2=1,2,…,n) Ax≥0,∴∑f(5,)Ax≥0, =max{△x1,△x2,…,△xn} imnf(5)Ax=f(x)d≥0dx b a   1 dx b a = = b − a. 则 ( )  0  f x dx b a . (a  b) 证  f (x)  0,  ( )  0, i f (i = 1,2,  ,n)   0,  xi ( ) 0, 1      = i i n i f x max{ , , , }  = x1 x2  xn i i n i   f x = → lim ( ) 1 0   ( ) 0.  =  b a f x dx 性质4 性质5 如果在区间[a,b]上 f (x)  0