七年级已知n是正整数,且a^2n=3,求(3a^3n)^2-13(a^2)^2n的值

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/21 00:31:39
七年级已知n是正整数,且a^2n=3,求(3a^3n)^2-13(a^2)^2n的值
x){-w-}KXlgS

七年级已知n是正整数,且a^2n=3,求(3a^3n)^2-13(a^2)^2n的值
七年级已知n是正整数,且a^2n=3,求(3a^3n)^2-13(a^2)^2n的值

七年级已知n是正整数,且a^2n=3,求(3a^3n)^2-13(a^2)^2n的值
(3a^3n)^2-13(a^2)^2n
=3^2*a^6n-13a^4n
=9*(a^2n)^3-13(a^2n)^2
=9*3^3-13*3^2
=243-117
=126

(3a^3n)^2-13(a^2)^2n
=9a^6n-13a^4n
=9(a^2n)^3-13(a^2n)^2
=9*3^3-13*3^2
=126

27*27-13*9=612