^表示次方
(x的2m)3次方+(y的n次方)3次方—x的2m次方×y的n次方×X的4m次方×y的2n次方
=x^6m+y^3n-x^6my^3n
=(x^3m)^2+y^3n-(x^3m)^2y^3n
因为
x^3m=4
y^3n=5
原式
=4^2+5-4^2*5
=16+5-16*5
=21-80
=-59