已知x^2n=2(n是正整数),求(3x^2n)^2-4(x^2)^2n的值
问题描述:
已知x^2n=2(n是正整数),求(3x^2n)^2-4(x^2)^2n的值
答
(3x^2n)^2-4(x^2)^2n
=9x^(4n)-4x^(4n)
=5x^(4n)
=5[x^(2n)]²
=5*2²
=20