将x=2,y=-4代入ax*3+1/2by+5=1997
得4a-b=996
将x=-4,y=-1/2代入3ax-24by*3+4986
得3ax-24by*3+4986
=-12a+3b+4986
=-3(4a-b)+4986
=-3*996+4986
=1998
将x=2,y=-4代入ax*3+1/2by+5=1997
得4a-b=996
将x=-4,y=-1/2代入3ax-24by*3+4986
得3ax-24by*3+4986
=-12a+3b+4986
=-3(4a-b)+4986
=-3*996+4986
=1998