1/(x-2),1/(3x+6),3/(x³-4x)看分母x-2,3x+6=3(x+2),x³-4x=x(x²-4)=x(x+2)(x-2)所以通分后是3x(x+2)/[3x(x+2)(x-2)],x(x-2)/[3x(x+2)(x-2)],9/[3x(x+2)(x-2)]