如图:点A在双曲线上,AB丄x轴于B,且△AOB的面积S△AOB=2,则k= .
计算:(a+2b)(a-b)=_________;
填空:x2y·( )=2x3y-x2y2.
计算:3x2y(-4xy2)·(x3)2=_________.
计算:x2y3·xyz=_________;
计算:2ab2·a3=________;