a^3m=4.b^2n=5
(a^2m)^3=(a^3m)^2=4^2=16
(b^n)^3=(b^2n)^(3/2)=5√5
a^2m=(a^3m)^(2/3)=4^(2/3)
(a的2m次方)的3次方+(b的n次方）的3次方-a的2m次方
=16+5√5-4^(2/3)