若n为正整数,a的2n次方=5,则2a的6n次方-4=

问题描述:

若n为正整数,a的2n次方=5,则2a的6n次方-4=

2a的6n次方-4=a的2n次方*a的2n次方*a的2n次方-4=5*5*5-4=121.

^ 表示乘方
a^2n=5
2a^6n-4
=2×(a^2n)³-4
=2×5³-4
=2×125-4
=250-4
=246