化简代数式x

x2−1x2+2x÷x−1x=x2−1x2+2x•xx−1=(x −1)(x+1)x(x +2)•xx−1=x+1x+2，不等式组x+2＜1①2(x−1)＞−6②，解不等式①，得x＜-1．解不等式②，得x＞-2．∴不等式组x+2＜12(x−1)＞−6的解集是-2＜x＜-1．∴当-2＜x＜-1时，x+1＜0，x+2＞0，∴x+1x+2＜0，即该代数式的符号为负号．