һѡ
1.()f(x)=x|x+a|+b溯ijҪ( )
A.ab=0 B.a+b=0 C.a=b D.a2+b2=0
2.()a=1Ǻy=cos2ax-sin2axСΪС( )
A.ֲҪ B.Ҫ
C.Ҫ D.ȷdzҲDZҪ
3.()a=3ֱax+2y+3a=0ֱ3x+(a-1)y=a-7ƽҲغϵ_________.
4.()AF(x,y)=0G(x,y)=0ཻڵP(x0,y0),BF(x,y)+G(x,y)=0(Ϊ)P(x0,y0),AB__________.
5.()Ƿx2-ax+b=0ʵԷa>2b>1¾1ʲô?
6.()֪{an}{bn}㣺bn= ,֤{an}ɵȲеijҪ{bn}ҲǵȲ.
7.()֪Cy=-x2+mx-1͵A(30)B(03)C߶ABͬijҪ.
8.()p:-2
ο
ѵų
֤(1)ԣΤﶨ|b|=|·|=||·||<2×2=4.
f(x)=x2+ax+b,f(x)ͼǿϵ.
||<2,||<2,f(±2)>0.
4+b>2a>-(4+b)
|b|<4 4+b>0 2|a|<4+b
(2)Ҫԣ
2|a|<4+b f(±2)>0f(x)ͼǿϵ.
f(x)=0ͬ(-22)ڻʵ.
ߦǷf(x)=0ʵ
ͬ(-22)ڣ||<2||<2.
ѵѵ
һ1.a2+b2=0,a=b=0,ʱf(-x)=(-x)|x+0|+0=-x·|x|=-(x|x+0|+b)
=-(x|x+a|+b)=-f(x).
a2+b2=0f(x)Ϊ溯ijf(x)=x|x+a|+b溯f(-x)=
(-x)|(-x)+a|+b=-f(x),a=b=0,a2+b2=0.
a2+b2=0f(x)Ϊ溯ıҪ.
𰸣D
2.a=1,y=cos2x-sin2x=cos2x,ʱyСΪ.a=1dzy=cos2ax-sin2ax=cos2ax.ʺyСΪ,a=±1,a=1DZҪ.
𰸣A
3.a=3ʱֱl1:3x+2y+9=0;ֱl2:3x+2y+4=0.l1l2A1A2=B1B2=11C1C2=941,C1C2,a=3 l1l2.
𰸣Ҫ
4.P(x0,y0)F(x,y)=0G(x,y)=0Ľ㣬F(x0,y0)+G(x0,y0)=0F(x,y)+G(x,y)=0P(x0,y0);֮.
𰸣ֲҪ
5.⣺Τﶨa=+,b=.жp: q: (עpabǰǦ=a2-4b0)
(1) a=+>2,b=>1,q p
(2)Ϊ֤p q,Ծٳȡ=4,= ,a=+=4+ >2,b==4× =2>1,q.
ۿ֪a>2,b>1Ǧ>1,>1ıҪ.
6.֤ٱҪԣ
{an}ɵȲУΪd,{an}ɵȲ.
Ӷbn+1-bn=a1+n· d-a1-(n-1) d= dΪ.
{bn}ǵȲУΪ d.
ڳ:
{bn}ǵȲУΪd,bn=(n-1)d䪤
bn(1+2++n)=a1+2a2++nan
bn-1(1+2++n-1)=a1+2a2++(n-1)an
-ڵãnan= bn-1
an= ,Ӷan+1-an= dΪ{an}ǵȲ.
{an}ɵȲеijҪ{bn}ҲǵȲ.
7.⣺ٱҪԣ
֪ã߶ABķΪy=-x+3(0x3)
C߶ABͬĽ㣬
Է *ͬʵ.
Ԫãx2-(m+1)x+4=0(0x3)
f(x)=x2-(m+1)x+4,
ڳԣ
3
x1= >0
x2-(m+1)x+4=0ȵʵx1,x2,0
ˣy=-x2+mx-1߶ABͬijҪ3
8.⣺xķx2+mx+n=02С1Ϊx1,x2.
0
Τﶨ -2
֮ȡm=- <0
x2+mx+n=0ʵp q
pqıҪ.
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