题目

— What did Tina say? —     Sorry, I didn’t________ what she said. A. pay attention to   B. get on with   C. hold on to    D. look forward to 答案：A已知关于x的方程x2+（m+2）x+2m-1=0（m为实数），（1）求证：方程有两个不相等的实数根；（2）当m为何值时，方程的两根互为相反数并求出此时方程的解．