题目

 (08·湖南B篇) Most young architects—particularly those in big cities—can only dream about working in a building of their own.And making that dream come true often means finding a building no one else seems to want,which is exactly what happened to David Yocum and his partner,Brian Bell.Their building is a former automobile electrical-parts firm in Atlanta.From the outside,it looks too old,even something horrible,but open the door and you are in a wide,open courtyard,lined on three sides with rusting(生锈的) walls. In 2000,Yocum and Bell found this building in the city’s 如图，在平面直角坐标系中，直线l1：y=﹣x与反比例函数y=的图象交于A，B两点（点A在点B左侧），已知A点的纵坐标是2：（1）求反比例函数的表达式；（2）将直线l1：y=﹣x向上平移后的直线l2与反比例函数y=在第二象限内交于点C，如果△ABC的面积为30，求平移后的直线l2的函数表达式．