.已知两直线l1:x+8y+7=0和l2:2x+y﹣1=0. (1)求l1与l2交点坐标; (2)求过l1与l2交点且与直线x+y+1=0平行的直线方程. 答案:解:(1)联立两条直线的方程可得: 解得x=1,y=﹣1 , 所以l1与l2交点坐标是(1,﹣1). (2)设与直线x+y+1=0平行的直线l方程为x+y+c=0 因为直线l过l1与l2交点(1,﹣1) , 所以c=0 , 所以直线l的方程为x+y=0. Two desks and one chair in the room. A. am B. is C. are D. be