题目

In the next picture (be) my brother Tom and his friend. 答案：【1】are椭圆C：x29+y24=1，斜率为k的直线l与椭圆相交于点M，N，点A是线段MN的中点，直线OA（O为坐标原点）的斜率是k′，那么kk′=-49-49．