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[函数] 被一折线题目折磨了

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realnumber posted 2015-4-20 10:07 |Read mode
Last edited by realnumber 2015-4-20 11:04当且仅当$x\in (a,b)∪(c,d)$,($b\le c$),$f(x)=2x^2+x+2$的图象在函数$g(x)=\abs{2x+1}+\abs{x-t}$的图象的下方,则$b-a+d-c$的取值范围.

经过分类讨论.
$t\le-0.5$三条,不合题意,写得自己都不满意,不写出来了.
$t\ge -0.5$,经过分三类.$2x^2+x+2=3x+1-t$无解;$2x^2+x+2=x+1+t$得到$t>1$;$2x^2+x+2=-3x-1+t$,且$f(-0.5)>g(-0.5)$,得出$t<1.5$.
得出$1<t<1.5$.
$b-1+d-c\in (0,2)$
$type

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其妙 posted 2015-4-20 23:38
1blog图片.jpg
妙不可言,不明其妙,不着一字,各释其妙!

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kuing posted 2015-4-21 01:00
读完题就不想做的赶脚……

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