a/(a^2+a+1)=1/6,求a^2/(a^4+a^2+1).
已知两边同时取倒数,得:
(a^2+a+1)/a=6
a+1+1/a=6
a+1/a=5
先求:
(a^4+a^2+1)/a^2
=a^2+1+1/a^2
=(a^2+1/a^2+2)-1
=(a+1/a)^2-1
=5^2-1
=25-1
=24
所以:
a^2/(a^4+a^2+1)=1/24
a/(a^2+a+1)=1/6,求a^2/(a^4+a^2+1).
已知两边同时取倒数,得:
(a^2+a+1)/a=6
a+1+1/a=6
a+1/a=5
先求:
(a^4+a^2+1)/a^2
=a^2+1+1/a^2
=(a^2+1/a^2+2)-1
=(a+1/a)^2-1
=5^2-1
=25-1
=24
所以:
a^2/(a^4+a^2+1)=1/24