10. 解:(1)∵點(diǎn)在反比例函數(shù)圖象上,
∴,
即反比例函數(shù)關(guān)系式為;
∵點(diǎn)在反比例函數(shù)圖象上,
∴,
∵點(diǎn)和在一次函數(shù)的圖象上,
∴,
解得,
∴一次函數(shù)關(guān)系式為.
(2)當(dāng)時(shí),一次函數(shù)值為2,
∴,
∴.
9. 乙題:
解:(1)因?yàn)榉幢壤瘮?shù)的圖象經(jīng)過(guò)點(diǎn)
有,················································································································ 2分
.····················································································································· 3分
所以反比例函數(shù)的解析式為,············································································· 4分
(2)當(dāng)為一、三象限角平分線(xiàn)與反比例函數(shù)圖像的交點(diǎn)時(shí),
線(xiàn)段最短.············································································································ 5分
將代入,解得,即,.····················· 6分
,··········································································································· 7分
則,··········································································································· 8分
又為反比例函數(shù)圖像上的任意兩點(diǎn),
由圖象特點(diǎn)知,線(xiàn)段無(wú)最大值,即.·················································· 9分
8.解:(1)∵反比例函數(shù)的圖像經(jīng)過(guò)點(diǎn)A(1,3),
∴,即m=-3.
∴反比例函數(shù)得表達(dá)式為. ……3分
∵一次函數(shù)y=kx+b的圖像經(jīng)過(guò)A(1,-3)、C(0,-4),
∴ 解得
∴一次函數(shù)的表達(dá)式為y=x-4 ……3分
(2)由消去y,得x2-4x+3=0.
即(x-1)(x-3)=0.
∴x=1或x=3.
可得y=-3或y=-1.
于是或
而點(diǎn)A的坐標(biāo)是(1,-3),
∴點(diǎn)B的坐標(biāo)為(3,-1)! ……2分
7. 解:(1)設(shè)藥物燃燒階段函數(shù)解析式為,由題意得:
························································································································ 2分
.此階段函數(shù)解析式為······································································· 3分
(2)設(shè)藥物燃燒結(jié)束后的函數(shù)解析式為,由題意得:
·························································································································· 5分
.此階段函數(shù)解析式為······································································ 6分
(3)當(dāng)時(shí),得···················································································· 7分
························································································································· 8分
·························································································································· 9分
從消毒開(kāi)始經(jīng)過(guò)50分鐘后學(xué)生才可回教室.···························································· 10分
6. 解 (Ⅰ)∵點(diǎn)P(2,2)在反比例函數(shù)的圖象上,
∴.即. ···································································································· 2分
∴反比例函數(shù)的解析式為.
∴當(dāng)時(shí),. ···························································································· 4分
(Ⅱ)∵當(dāng)時(shí),;當(dāng)時(shí),, ····················································· 6分
又反比例函數(shù)在時(shí)值隨值的增大而減小, ············································· 7分
∴當(dāng)時(shí),的取值范圍為.································································ 8分
5. (1)證明:分別過(guò)點(diǎn)C、D作
垂足為G、H,則
(2)①證明:連結(jié)MF,NE
設(shè)點(diǎn)M的坐標(biāo)為,點(diǎn)N的坐標(biāo)為,
∵點(diǎn)M,N在反比例函數(shù)的圖象上,
∴,
由(1)中的結(jié)論可知:MN∥EF。
②MN∥EF。
4. 解:(1)由題意可知,.
解,得 m=3. ………………………………3分
∴ A(3,4),B(6,2);
∴ k=4×3=12. ……………………………4分
(2)存在兩種情況,如圖:
①當(dāng)M點(diǎn)在x軸的正半軸上,N點(diǎn)在y軸的正半軸
上時(shí),設(shè)M1點(diǎn)坐標(biāo)為(x1,0),N1點(diǎn)坐標(biāo)為(0,y1).
∵ 四邊形AN1M1B為平行四邊形,
∴ 線(xiàn)段N1M1可看作由線(xiàn)段AB向左平移3個(gè)單位,
再向下平移2個(gè)單位得到的(也可看作向下平移2個(gè)單位,再向左平移3個(gè)單位得到的).
由(1)知A點(diǎn)坐標(biāo)為(3,4),B點(diǎn)坐標(biāo)為(6,2),
∴ N1點(diǎn)坐標(biāo)為(0,4-2),即N1(0,2); ………………………………5分
M1點(diǎn)坐標(biāo)為(6-3,0),即M1(3,0). ………………………………6分
設(shè)直線(xiàn)M1N1的函數(shù)表達(dá)式為,把x=3,y=0代入,解得.
∴ 直線(xiàn)M1N1的函數(shù)表達(dá)式為. ……………………………………8分
②當(dāng)M點(diǎn)在x軸的負(fù)半軸上,N點(diǎn)在y軸的負(fù)半軸上時(shí),設(shè)M2點(diǎn)坐標(biāo)為(x2,0),N2點(diǎn)坐標(biāo)為(0,y2).
∵ AB∥N1M1,AB∥M2N2,AB=N1M1,AB=M2N2,
∴ N1M1∥M2N2,N1M1=M2N2.
∴ 線(xiàn)段M2N2與線(xiàn)段N1M1關(guān)于原點(diǎn)O成中心對(duì)稱(chēng).
∴ M2點(diǎn)坐標(biāo)為(-3,0),N2點(diǎn)坐標(biāo)為(0,-2). ………………………9分
設(shè)直線(xiàn)M2N2的函數(shù)表達(dá)式為,把x=-3,y=0代入,解得,
∴ 直線(xiàn)M2N2的函數(shù)表達(dá)式為.
所以,直線(xiàn)MN的函數(shù)表達(dá)式為或. ………………11分
(3)選做題:(9,2),(4,5). ………………………………………………2分
3. 解:(1) ………(每個(gè)點(diǎn)坐標(biāo)寫(xiě)對(duì)各得2分)………………………4分
(2) ∵ ∴…1分
∴ …………………1分
∴ …………………2分
(3) ① ∵
∴相應(yīng)B點(diǎn)的坐標(biāo)是 …………………………………………1分
∴. ………………………………………………………………1分
、 能 ……………………………………………………………………1分
當(dāng)時(shí),相應(yīng),點(diǎn)的坐標(biāo)分別是,
經(jīng)經(jīng)驗(yàn):它們都在的圖象上
…………………………………………………………………1分
2. 解:(1)(-4,-2);(-m,-)
(2) ①由于雙曲線(xiàn)是關(guān)于原點(diǎn)成中心對(duì)稱(chēng)的,所以O(shè)P=OQ,OA=OB,所以四邊形APBQ一定是平行四邊形
②可能是矩形,mn=k即可
不可能是正方形,因?yàn)镺p不能與OA垂直。
解:(1)作BE⊥OA,
∴ΔAOB是等邊三角形
∴BE=OB·sin60o=,
∴B(,2)
∵A(0,4),設(shè)AB的解析式為,所以,解得,的以直線(xiàn)AB的解析式為
(2)由旋轉(zhuǎn)知,AP=AD, ∠PAD=60o,
∴ΔAPD是等邊三角形,PD=PA=
1. 證明:(1)分別過(guò)點(diǎn)C,D,作CG⊥AB,DH⊥AB,
垂足為G,H,則∠CGA=∠DHB=90°.……1分
∴ CG∥DH.
∵ △ABC與△ABD的面積相等,
∴ CG=DH. …………………………2分
∴ 四邊形CGHD為平行四邊形.
∴ AB∥CD. ……………………………3分
(2)①證明:連結(jié)MF,NE. …………………4分
設(shè)點(diǎn)M的坐標(biāo)為(x1,y1),點(diǎn)N的坐標(biāo)為(x2,y2).
∵ 點(diǎn)M,N在反比例函數(shù)(k>0)的圖象上,
∴ ,.
∵ ME⊥y軸,NF⊥x軸,
∴ OE=y1,OF=x2.
∴ S△EFM=, ………………5分
S△EFN=. ………………6分
∴S△EFM =S△EFN. ……
由(1)中的結(jié)論可知:MN∥EF. ………8分
② MN∥EF. …………………10分
(若學(xué)生使用其他方法,只要解法正確,皆給分.
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