1.化简(1-1/x-1)/(x/x^-1)在选择一个适当的x求值解(1-1/(x-1))/(x/(x^-1))=((x-2)/(x-1))/(x/(x+1)(x-1))=(x-2)/(x-1)*(x+1)(x-1)/x=(x-2)(x+1)/x当x=2时,原式=0x适当的值一定不能是1,-1,02.、1/2(x+y+z)方+1/2(x-y-...