(2x+y)(x-3y)=2x(x-3y)+y(x-3y);y(x-3y)+y(x+3y)=2xy;所以2x(x-3y)+2xy=2x(x-3y+y)=2x(x-2y);
2x(x-2y)÷(2x)=x-2y能连住写下吗？这样还不太清楚[(2x+y)(x-3y)+y(x+3y)]÷(2x)=[2x(x-3y)+y(x-3y)+y(x+3y)]÷(2x)=[2x(x-3y)+y(x-3y+x+3y)]÷(2x)=[2x(x-3y)+2xy]÷(2x)=x-3y+y或者=[2x(x-3y+y)]÷2x=x-2y