一選
1.()f(x)=x|x+a|+b婧騁? )
A.ab=0 B.a+b=0 C.a=b D.a2+b2=0
2.()a=1嗆y=cos2ax-sin2ax小為小( )
A.植要 B.要
C.要 D.確淺也潛要
3.()a=3直ax+2y+3a=0直3x+(a-1)y=a-7平也睪系_________.
4.()AF(x,y)=0G(x,y)=0嘟悔礟(x0,y0),BF(x,y)+G(x,y)=0(為)P(x0,y0),AB__________.
5.()欠x2-ax+b=0實苑a>2b>1戮1什么?
6.()知{an}{bn}悖篵n= ,證{an}傻炔械某要{bn}也塹炔.
7.()知Cy=-x2+mx-1偷A(chǔ)(30)B(03)C叨AB同某要.
8.()p:-2
慰
訓懦
證(1)裕韋鋃▅b|=|·|=||·||<2×2=4.
f(x)=x2+ax+b,f(x)圖強系.
||<2,||<2,f(±2)>0.
4+b>2a>-(4+b)
|b|<4 4+b>0 2|a|<4+b
(2)要裕
2|a|<4+b f(±2)>0f(x)圖強系.
嚳絝(x)=0同(-22)諢實.
搟欠f(x)=0實
同(-22)冢||<2||<2.
訓訓
一1.a2+b2=0,a=b=0,時f(-x)=(-x)|x+0|+0=-x·|x|=-(x|x+0|+b)
=-(x|x+a|+b)=-f(x).
a2+b2=0f(x)為婧砯(x)=x|x+a|+b婧痜(-x)=
(-x)|(-x)+a|+b=-f(x),a=b=0,a2+b2=0.
a2+b2=0f(x)為婧幣?
鳶福D
2.a=1,y=cos2x-sin2x=cos2x,時y小為.a=1淺y=cos2ax-sin2ax=cos2ax.屎y小為,a=±1,a=1潛要.
鳶福A
3.a=3時直l1:3x+2y+9=0;直l2:3x+2y+4=0.l1l2A1A2=B1B2=11C1C2=941,C1C2,a=3 l1l2.
鳶福要
4.P(x0,y0)F(x,y)=0G(x,y)=0慕�，F(xiàn)(x0,y0)+G(x0,y0)=0F(x,y)+G(x,y)=0P(x0,y0);之.
鳶福植要
5.猓何わ定a=+,b=.卸p: q: (注pab前鉛=a2-4b0)
(1) a=+>2,b=>1,q p
(2)為證p q,躍儷取=4,= ,a=+=4+ >2,b==4× =2>1,q.
劭知a>2,b>1鉛>1,>1謀要.
6.證儔要裕
{an}傻炔校為d,{an}傻炔.
傭bn+1-bn=a1+n· d-a1-(n-1) d= d為.
{bn}塹炔校為 d.
誄:
{bn}塹炔校為d,bn=(n-1)d洫?/p>
bn(1+2++n)=a1+2a2++nan
bn-1(1+2++n-1)=a1+2a2++(n-1)an
-詰茫nan= bn-1
an= ,傭an+1-an= d為{an}塹炔.
{an}傻炔械某要{bn}也塹炔.
7.猓嘿幣?/p>
知茫叨AB姆為y=-x+3(0x3)
C叨AB同慕悖?/p>
苑 *同實.
元茫x2-(m+1)x+4=0(0x3)
f(x)=x2-(m+1)x+4,
誄裕
3
x1= >0
嚳絰2-(m+1)x+4=0鵲實x1,x2,0
耍y=-x2+mx-1叨AB同某要3
8.猓簒姆x2+mx+n=02小1為x1,x2.
0
韋鋃?-2
之取m=- <0
x2+mx+n=0實p q
pq謀要.
2017煽猓?/strong>2017爍嚦史憑學模
2017煽2017爍嚦時/
