计算：3xy[2xy-x（y-2）+x]
问题描述：
计算：3xy[2xy-x（y-2）+x]
答
3xy[2xy-x（y-2）+x]
＝3xy[2xy-xy+2x+x]
=3xy(xy+3x)
=3x²y²+9x²y