已知:a2+4a+1=0,且a4+ma2+12a3+ma2+2a=3,求m的值.

问题描述:

已知:a2+4a+1=0,且

a4+ma2+1
2a3+ma2+2a
=3,求m的值.

∵a2+4a+1=0,∴a2+1=-4a,
∴(a2+1)2=16a2
∴a4+2a2+1=16a2
即a4+1=14a2

a4+ma2+1
2a3+ma2+2a
=3,
14a2+ma2
2a(a2+1)+ma2
=3,
整理得14a2+ma2=-24a2+3ma2
∴(38-2m)a2=0,
∵a≠0,∴38-2m=0,
∴m=19.
答案解析:由a2+4a+1=0,得出a2+1=-4a,则(a2+1)2=16a2,从而求得a4+1=14a2,再代入
a4+ma2+1
2a3+ma2+2a
=3
,求值即可.
考试点:分式的化简求值.
知识点:本题考查了分式的化简求值,解答此题的关键是把已知的式子变形,然后整体代入即可.