Question

已知n为正整数,且(x的n次)2次=9,求(x的3n次)2次-3(x的2次)2n次的值

Answer 1

已知,(x^n)^2 = 9 ,可得：x^(2n) = 9 .

[x^(3n)]^2-3[(x^2)^(2n)] = x^(6n)-3x^(4n) = [x^(2n)]^3-3[x^(2n)]^2 = 9^3-3*9^2 = 486 .