若x的3n次方=5,y的2n次方=4,则x的6n次方+y的4n次方等于?

题目

若x的3n次方=5,y的2n次方=4,则x的6n次方+y的4n次方等于?

答案

x^(6n)+y^(4n)
= [x^(3n)]^2 + [y^(2n)]^2
= 5×5 + 4×4
= 25 + 16
= 41