计算:a2•5a= .
若单项式2a2bx﹣y与﹣3ax+yb4是同类项,则x=______,y=______.
若单项式x2yn与﹣2xmy3的和仍为单项式,则nm的值为______.
已知x6y2与﹣3x3myn﹣2是同类项,则5m﹣3n的值为______.
若a2bm和anb3是同类项,则m﹣n=______.
若单项式与的差仍是单项式,则m﹣2n= ______.