一道easy的数学题.已知x+（1/x）=4,则x^2/（x^4+x^2+1）=?

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已知x+1/x=4,则x^2/(x^4+x^2+1)=?
(x^4+x^2+1)/x^2
=x^2+1+1/x^2
=x^2+1/x^2+1
=(x+1/x)^2-2+1
=4^2-1
=16-1=15所以：x^2/(x^4+x^2+1)=1/15.
======以下答案可供参考======
供参考答案1:
你上几年级供参考答案2:
x+（1/x）=4
(x^2+1)/x=4
x^2=4x-1
x^2/（x^4+x^2+1）=(4x-1)/((4x-1)^2+(4x-1)+1)
=(4x-1)/(16x^2-8x+1+4x)
=(4x-1)/(16(4x-1)-8x+1+4x)
=(4x-1)/(16(4x-1)-4x+1)
=(4x-1)/15(4x-1)
=1/15