题目

不等式x+1＞3的解集是（ ）                                                             A．x＞1                       B．x＞﹣2                    C．x＞2                       D．x＜2 答案：C【分析】移项、合并同类项即可求解．                                                  【解答】解：移项，得x＞3﹣1，                                                             合并同类项，得x＞2．                           �若实数x、y、z满足x2+y2+z2=1，则xy+yz+zx的取值范围是A.[-1，1]B.[-，1]C.[-1，]D.[-，]