若9x2+kx+1是一个完全平方式，则k=_____．
6 a2 x3·（_________）=36 a4 x5-24 a3 x4+18 a2 x3．
3an+1÷2 an＝_________.
计算:(16x2y3z+8x3y2z)÷8x2y2=__________.
______.
计算 =______________
______.
=______________