性质6(保序性) 若在[a,b](a<b)上f(x)≤g(x),则 f(x xs g(xddx 性质7(定积分的绝对值不等式) Jf(x)川f(x)x(a<b -f(x)≤f(x)≤1f(x) lf()kxs f(xydxslf(x)kxf x dx g x dx b a b a  ( )  ( ) 性质6(保序性) 若在[a,b](a<b)上f(x)≤g(x),则 | f (x)dx | | f (x)|dx (a b) b a b a     性质7(定积分的绝对值不等式) ∵−|f(x)|≤f(x)≤|f(x)| f x dx f x dx f x dx b a b a b a   − | ( )|  ( )  | ( )|