性质1 若[f(x)与f(x)bx都收敛,k1,k2为任意常数,则 [k1f1(x)+k2,f2(x)x也收敛,且 Tk f(x)+k,f2(x)]dx=k,l f(x)dx+kal f2(x)dx 性质2 若任何有限区间a,n上可积,a<b 则f(x)与f(x)bx同敛散,且 r f(x)dx=5/()dx+5f(xxx一 . 无穷积分的性质 性质１ 若 f x dx与 f x dx都收敛，k k 为任意常数， 则 a a 1 2 1 2 ( ) ( ) ,   + + k f x k f x dx也收敛， 且 a [ ( ) ( )]  1 1 + 2 2 +    + + + + = + a a a [k f (x) k f (x)]dx k f (x)dx k f (x)dx. 1 1 2 2 1 1 2 2 性质２ 若f在任何有限区间[a,u]上可积，a  b 则 f x dx与 f x dx同敛散， 且 a b + + ( ) ( ) f (x)dx f (x)dx f (x)dx. b b a a  + + = +