题目内容
已知:a2+4a+1=0,且
=3,则m的值为______.
| a4+ma2+1 |
| 2a3+ma2+2a |
∵a2+4a+1=0,∴a2=-4a-1,
=
=
=
=
=3
即(-56-4m)a-14-m=(-12m+96)a-3m+24,
∴-56-4m=-12m+96,-14-m=-3m+24,
解得m=19.
故答案为19.
| a4+ma2+1 |
| 2a3+ma2+2a |
| (-4a-1)2+ma2+1 |
| 2a(-4a-1)+ma2+2a |
=
| (16+m)a2+8a+2 |
| (m-8)a2 |
=
| (16+m)(-4a-1)+8a+2 |
| (m-8)(-4a-1) |
=
| (-56-4m)a-14-m |
| (-4m+32)a-m+8 |
即(-56-4m)a-14-m=(-12m+96)a-3m+24,
∴-56-4m=-12m+96,-14-m=-3m+24,
解得m=19.
故答案为19.
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