函数f(x)=x^2/(x-1)　（ｘ属于Ｒ且ｘ不等于１）的单调递增区间是　（）Ａ.(负无穷,0)和(2,正无穷)B.(负无穷,0)C.(负无穷,1-根号2)和(根号2,正无穷)D.(2,正无穷)请简要写出过程.谢谢!!!