x=2,y=-4时,代数式ax的3次方+1/2by+5=2009
8a-2b+5=2009
8a-2b=2004
4a-b=1002
x=-4,y=1/2时,
3ax-24by的3次方+5016
=-12a+3b+5016
=-3(4a-b)+5016
=-3*1002+5016
=-3006+5016
=2010
x=2,y=-4时,代数式ax的3次方+1/2by+5=2009
8a-2b+5=2009
8a-2b=2004
4a-b=1002
x=-4,y=1/2时,
3ax-24by的3次方+5016
=-12a+3b+5016
=-3(4a-b)+5016
=-3*1002+5016
=-3006+5016
=2010