1.已知求2.已知求注：（f o g)=f{g(x)}     &nb

1。(f○g)(x)=f(g(x))=-5/(2(g(x))+2)=-5/((-5-2x)/x+2)=x(g○f)(x)=g(f(x))=(-5-2(-5/2x+2))/2(-5/2x+2)=x2。(f○g)(x)=f(g(x))=（3√x+3)^3-3=x+3-3=x(g○f)(x)=g(f(x))=3√(x^3-3)+3==3√(x)^3=x