已知n为正整数,且(xn)2 =9,求(1/3x3n)2-3(x2)2n的值.
问题描述:
已知n为正整数,且(xn)2 =9,求(
x3n)2-3(x2)2n的值. 1 3
答
∵(xn)2 =9,
∴x2n=9,
∴原式=
(x2n)3-3(x2n)21 9
=
×93-3×921 9
=-162.