已知a눀-3a+1=0,求a⼀a^4+1的值

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2024-12-26 01:40:51
推荐回答(2个)
回答1:

∵a²-3a+1=0
∴a²=3a-1
则a^4=(3a-1)^2
=9a^2-6a+1
(将a²=3a-1代入)
a^4=9(3a-1)-6a+1
=21a-8
那么a^4+1=21a-8+1
=21a-7
=7(3a-1)
(将a²=3a-1代入)
则a^4+1=7a^2
所以a/(a^4+1)=a/7a^2
=1/(7a)

回答2:

已知a²-3a+1=0可得:a-3+1/a=0,a+1/a=3
a/(a^4+1)
=(1/a)/(a^2+1/a^2)
=(1/a)/[(a+1/a)^2-2]
=(1/a)/7
请问下,是求a/(a^4+1)还是a^2/(a^4+1)?