不定积分的性质 lIf(x)+g(x]dx=l f(xdx+ g(x)dx (2) kf ()dx=k f(x dx (k是常数,k≠0)不定积分的性质    (1) [ f (x) g(x)]dx = f (x)dx  g(x)dx   (2) kf (x)dx = k f (x)dx (k是常数, k0)