1ï¼Pæ¯ä¸ä¸ªæç©çº¿y 2 = 4åçç¹Pçç¹çç´çº¿çè·ç¦»ç4å3?15 = 0æ¶ï¼æå°å¼ä¸ºï¼
溶液ï¼è®¾å®ç¹Pçç´çº¿è·ç¦»e
设å®ç¹Pçåæ ï¼Y 2/4 yï¼ç
代以è·ç¦»å
¬å¼
D = | Y 2 + 1612 +15 /âï¼4 +3ï¼=ï¼Y +3 / 2ï¼2 +51 / 4/5
æ¾ç¶ï¼Y = -3 / 2ï¼y 2 +3?+15æå°å¼ä¸º51/4çç¹Pçç´çº¿è·ç¦»æå°æ¯äºååä¹äºåä¸ï¼
2ï¼å¨ç¬å¡å°åæ ç³»ç»ä¸ï¼æç©çº¿y =æ§2 + bx + cçä¸xè½´ç¸äº¤äºä¸ä¸ªï¼b两ç¹ï¼å¨å·¦è¾¹çç¹aï¼bç¹ï¼ï¼å¨Cç¹çyè½´ç交åç¹aï¼-3,0ï¼ï¼0,3ï¼çç¹cï¼åæç©çº¿ç对称轴æ¯x = -2 ï¼1ï¼å¦æPæ¯çº¿æ®µä¸çç¹éâ³ABPâ³BPCé¢ç§¯Sâ³ABP Sâ³BPCå°å·â³ABPæ¯Sâ³BPC = 2å3ï¼æ±pçåæ ï¼2ï¼è®¾ç½®ä¸å¿Qåå¾ä¸º1ï¼å¨æç©çº¿ç§»å¨çä¸å¿Qæ头ä¸å¨è¿å¨è¿ç¨ä¸ï¼æ 论æ¯ä¸å¿qåy-è½´ç¸åï¼ä¸qæ¯åæ
解å³æ¹æ¡ï¼ï¼1ï¼æ®çå«ä¹
é®é¢
对称轴x = -2
bç¹åæ 为ï¼-1,0ï¼
sçæ¯Sâ³BPCï¼ABPâ³= 2æ¯3çSâ³ ABPåSâ³BPCä¸åçåºé¨è½®å» APï¼PC = 2:3
OA 2 + OC 2 = AC 2
AC =â2
OA = OCè§åº¦OAC 45度
ç¶åç¹På°yè½´çè·ç¦»= ACÃ3/5Ãä½å¼¦è§OAC = 3â2/5Ãâ2/2?? = 9/5
ç¹på°xè½´çè·ç¦»= ACÃ2/5Ã罪è§OAC = 3â2Ã2/5Ãâ2/2?? = 6/5
å æ¤ï¼è¯¥ç¹çåæ Pï¼-9 / 5,6 / 5ï¼
ï¼2ï¼æ ¹æ®é¢æ设置äºæç©çº¿ç解æå¼ä¸ºy = ax 2 + BX +3
ï¼-3,0ï¼ï¼ï¼-2,0ï¼ï¼
9A -3B +3 = 0
4A解å³æ¹æ¡-2B +3 = 0
= 1/2ï¼B = -5 / 2
Y = 1/2X 2-5 / 2Ã3
ï¼ç¶åå¦ææqæåè£
ç½®çy-è½´çè·ç¦»ä»ç¹q = 1
ä¹å½x = 1æ-1æ¶
= -1ï¼Y = 0
x = 1æ¶ï¼ä¸ºy = 5
âï¼-1,0ï¼æï¼1,5ï¼
3ï¼ç´çº¿y =-6ç¸äº¤äºAç¹ï¼ä¸xè½´æ¹ååyè½´ç交ååç¹B线段ABçåCçç´å¾ï¼æç©çº¿y =æ§+ bx + cçè¶
Açå¹³æ¹çï¼Cï¼Oä¸ç§ã 1ï¼æ¾å°Cç¹çåæ åæç©çº¿ç解æ表达å¼ã 2éè¿Bç¹çç´çº¿ä¸xè½´ç¸äº¤äºç¹Dï¼åOBå¹³æ¹= OA * ODï¼éªè¯ï¼DBæ¯ä¸ä¸ªåCç¸åã 3ãæç©çº¿æ¯å¦åå¨çç¹Pï¼ä»è使ç´è§æ¢¯å½¢å边形ç顶ç¹Pï¼Oï¼Cï¼Aï¼å¦æåå¨çè¯ï¼å¾å°çç¹Pçåæ ï¼å¦æå®ä¸åå¨ï¼è¯´æã â
解å³æ¹æ¡ï¼å¾
1ï¼ä»¤X = 0åy = 0åAåB??åå«æ±åºåè°
ç¹Aï¼6,0ï¼ï¼Bï¼0,6ï¼ />çä¸å¿Cçåæ ï¼3,3ï¼
设å®æç©æ¹ç¨ä¸ºy = ax 2 + BX
ï¼3,3ï¼åï¼6,0ï¼ä»£å
¥
9A + B = 3
36A +6 = 0
解å³æ¹æ¡
= -1 / 3ï¼B = 2
æç©çº¿ç解æå¼ä¸ºy = -1/3x 2 + 2Ã
2ï¼
| OB | = 6ï¼| OD | = | X |ï¼| OA | = 6
æ ¹æ®è®¾ç½®çåæ çç¹Dï¼çxï¼0ï¼é¢æ
36 = | X |Ã6
X = -6æ??6ï¼åèäºå
¥ï¼ç
ç¹Dçåæ 为ï¼-6,0ï¼
|广å| = 12ï¼| AB | = 6â2ï¼| BD | = 6â2
| AB | 2 + | BD | 2 = |广ååç»| 2
æ以â ABD = 90度
> BDç¸åçå?
3ï¼ç¹P
| OA | = | OC | = 3â2ï¼| AC | = 3â2
| OC | 2 + | AC | 2 = | OA | 2
â OCA = 90°
Aç¹çå¹³è¡çº¿æ³å¢äº¤æç©çº¿äºç¹Pï¼äº¤yè½´äºç¹Eï¼Pç¹æ¯å¯»æ± BR />çå°ç±é¢æ
BDâOCâAPï¼åCæ¯ABçä¸ç¹
Oç¹çä¸ç¹ï¼ç¹Eçåæ ï¼0ï¼-6ï¼ç´APåç´çº¿ABåç´ï¼å æ¤APçç´çº¿çæçæ¯
ç´çº¿APçæ¹ç¨ä¸ºï¼y =çX -6
åæ¶
y = xçï¼1ï¼?? /> Y = -1/3x 2 +2 Xï¼2ï¼ï¼2ï¼
ï¼1ï¼ä»£
X-6 = -1/3x 2 +2æè¿°
ç®å
>Ã2-3X-18 = 0
ï¼X-6ï¼ï¼X 3ï¼= 0
= -3æx = 6ï¼èå
¥ï¼ç¶åçåæ çç¹Aï¼
= -3ï¼ä¸ºy = -9
è¿æ ·çç¹Pï¼-3ï¼-9ï¼
4ï¼å·²ç¥ç¹Pçåæ æ¯ä¸ä¸ªå½æ°y = 1 / 2Xï¼x> 0æ¶ï¼çç¹çå¾åï¼PAâ¥xè½´å¨ç¹Aï¼äº¤åå½æ°Y =ç1 / xï¼x> 0æ¶ï¼çå¾åå¨ç¹Mï¼PBâ¥Yè½´å¨ç¹ä¹ï¼äº¤åå½æ°y = 1 / Xï¼X> 0ï¼ï¼ç¹Nï¼MNç¹ä¸éåï¼
ï¼1ï¼å½ç¹Pç横åæ æ¯åæ¨2æ¶ï¼æ±â³PMNåº; />ï¼2ï¼è¯æï¼MNâABï¼å¾7ï¼
ï¼3ï¼é®ï¼â³OMNä¸ä¸ªç´è§ä¸è§å½¢åï¼å¯è½è¦æ±çç¹Pçåæ ;å¦æ没æï¼è¯·è§£éåå ã
解å³æ¹æ¡ï¼ï¼1ï¼Pç¹çæ°´å¹³åæ ï¼é£ä¹çºµåæ 为1
ç¹Pï¼2,1ï¼ï¼ï¼2,0ï¼ï¼Bï¼0,1ï¼
å¨x = 2代以为y = 1 / xçï¼ä¸ºy = 1/2ï¼å该ç¹çåæ Mï¼2,1 / 2ï¼ Y = 1代以为y = 1 / xçï¼x = 1æ¶ï¼ååæ ç¹N为ï¼1,1ï¼= 1/2
PN
PM = 1-1/2 = 2-1 = 1
Sâ³PMN = 1 / 2ÃPMæè¿°PN = 1/2Ã1/2Ã1 = 1/4
ï¼2ï¼
ç´çº¿ABæç=ï¼0-1ï¼/ï¼2-0ï¼= -1 / 2
æçç线MN =ï¼1/2-1ï¼/ï¼2-1ï¼= -1 / 2
é½æççäº
ABâMN
>ï¼3ï¼çç¹Pçåæ ï¼å»ºç«å¨ï¼2aï¼ä¸ï¼
çç¹Mçåæ æ¯ï¼2αï¼1/2Aï¼åæ çç¹Nï¼1 /αï¼Î±ï¼ AB线æç为-1 / 2ï¼â MONæ¾ç¶ä¸æ¯ç©å½¢
ä¸ç´çº¿ABåç´çç´çº¿çæ¹ç¨ä¸ºY = 2X
Y = 2X
> Y = 1 / X
åæ¶
Ã2 = 1/2
X =â2/2 - 2/2âï¼åèäºå
¥ï¼
Y =â2 /> Nç¹çåæ æ¯ï¼â2/2â2ï¼
ç¹Pç纵åæ æ¯â2ï¼å
³äºæºç 2ï¼æ¨ªè½´æ¯
ç¹Mæ¯ï¼2â2ï¼â2çåæ
åç´äºMNä¸è§å½¢OMN / 4ï¼æ¯ä¸ä¸ªç´è§ä¸è§å½¢
Pç¹çåæ 为ï¼2â2â2ï¼
ç¥éæç©çº¿y = AX 2 + BX + C X-轴交åAï¼B两ç¹ï¼ä¸yè½´ç交åç¹Cï¼è½´çXè½´æ£æ¹åä¸çBç¹ï¼Cç¹çyè½´çæ£åè½´ï¼æ®µOBï¼OCé¿ï¼OB <OCï¼æ¹ç¨x 2 - 10å16 = 0çä¸¤ä¸ªæ ¹åæç©çº¿ç对称轴æ¯ç´çº¿= -2ã
ï¼1ï¼è¡¨è¾¾å¼æ±æ¤æç©çº¿
ï¼2ï¼è¿æ¥ACï¼BCï¼Eç¹çº¿æ®µABä¸çä¸ä¸ªåºå®ç¹ï¼ç¹Aï¼ç¹Bä¸éåï¼ï¼å¨E EF / / AC交åç¹Fï¼è¿æ¥CEç»AEé¿åº¦ä¸ºmï¼â¿CEFé¢ç§¯ä¸ºS ï¼æ±çSåmä¹é´çå½æ°å
³ç³»ï¼ååå
¥ä»åémçèå´å
;
ï¼3ï¼å¨ï¼2ï¼æè¿°çæ大å¼Såå¨çåºç¡ä¸ï¼å¦æå®åå¨ï¼å该请æ±çå¾å°æ大çSå¼ï¼åç¹Eçåæ ï¼â¿BCEç¡®å®çå½¢ç¶;å¦æ请说æçç±ã
解å³æ¹æ¡ï¼ï¼1ï¼æ¹ç¨x 2-10Ã16 = 0 />ï¼2ï¼ï¼-8ï¼= 0
x = 2æ¶æx = 8
ç¶åOB = 2ï¼OC = 8
ç¹Bçåæ 为ï¼2,0ï¼ ï¼Cç¹ï¼0,8ï¼
éæç©çº¿å½æ°y = aï¼x +2ï¼2 + B
代
16A + B = 0ï¼1ï¼
4A + B = 8ï¼2ï¼
ï¼1ï¼ - ï¼2ï¼
12A = -8
= -2 / 3
B = 32/3ç
æç©çº¿æ¹ç¨ä¸ºy = -2 / 3ï¼x +2ï¼2 +32 / 3 = -2/3x 2 -8/3x + 8
ï¼2ï¼çåæ ç¹Aï¼-6,0ï¼ä¸çåæ x = -2æ¶ï¼åç¹ä¹å¯¹ç§°
ç¹Eç第ï¼m-6ï¼0ï¼
ç´çº¿ACçæç= 8/6 = 4/3
ç¶åEFçæç= 4/3
çç´çº¿BCçæ¹ç¨ä¸ºx / 2 + Y / 8 = 1
4X + Y = 8
设置ç´EFæ¹ç¨ä¸ºy = 4 / 3X + B
æ°ä¸ä»£çEç¹
0 = 4/3ï¼M-6ï¼+ B
B = 8-4 / 3M
ç´çº¿EFæ¹ç¨ä¸ºy = 4 +8-4/3ç±³/ 3å
4å+ Y = 8å¾å°ç交åç¹ï¼ç±³/ 4.8ç±³ï¼
Sâ³å
¬å¸= Sâ³ABC-Sâ³ACE-Sâ³BFE / = 1/2Ã8Ã8-1/2Ãç±³Ã8-1/2Ãï¼8ç±³ï¼Ãï¼8-mï¼ç
= -1 / 2ï¼ç±³-8ï¼2 -4M +32
-1/2m 2 +8 M-32-4M +32
= -1/2m 2 +4ç±³
0 <M <8
ï¼ 3ï¼S = -1/2m 24ç±³= -1 / 2ï¼å¹³æ¹ç±³ - 8ç±³ï¼= -1 / 2ç第ï¼m-4ï¼2 8
m = 4çå
·ææ大 > S = 8æ¶ï¼æ¤æ
åµä¸Eç¹çåæ ï¼-2,0ï¼
æ¯åå§æç©çº¿
â³BCEæ¯çè
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OE =çåç´å¹³å线ç对称轴BE BE = 2
ä¸ä¸»ç«æ¡æ³å¢ï¼â³BCEçè
°ä¸è§å½¢
度åä¹æ
天å âä½ä¸ºä¸ä¸ªæ°çæ»æ°´éï¼å
¶ä¸çé¨åPAï¼è½´ï¼è¡¨ç¤ºè·ç¦»åé«åº¦5ç±³çå¹³å°ï¼å¨è½´ä¸çç¹Pï¼çæ°´ãæ»éABçéå½æ°çå¾åçä¸é¨åï¼å¯ä»¥çåºï¼æ»æ§½BCDç å¯ä»¥è¢«è§ä¸ºäºæ¬¡å½æ°çå¾åï¼ä¸¤ä¸ªæ»æ§½è¿æ¥ç¹Bç顶ç¹çBCDçæç©çº¿çä¸é¨åï¼åç¹Bï¼ä»¥è¡¨é¢çè·ç¦»ä»BE =2ç±³ï¼Bç¹çy-è½´çè·ç¦»æ¯5ç±³ãå½å°æä»é¡¶é¨ä¸è·å°Cç¹ï¼ä¸æ°´ç表é¢è·ç¦»CG = 3/2ç±³ï¼ä¸Bç¹çè·ç¦»ï¼CF = 2ç±³ã
ï¼1ï¼æ±åå½æ°è§£æå®çåæ°èå´ã
ï¼2ï¼è§£å³èªåéèå´å
çäºæ¬¡å½æ°ã
ï¼3ï¼å°æå¨Dç¹ä»Aç¹æ»æ°´è¡¨é¢ï¼è¯çé®ä»æ»å¨æ°´å¹³è·ç¦»
解å³æ¹æ¡ï¼ï¼1ï¼
æ ¹æ®çå«ä¹é®é¢
æ们确å®äºå 个ç¹çåæ
Bï¼5,2ï¼ï¼Cï¼7,3 / 2ï¼
让AB解æå¼y = K / X
Bç¹å°
2 = K / 5
K = 10
AB解æå¼y = 10 / X
å½y = 5ï¼å½x = 2
ç¹Aï¼2,5ï¼
ä¸çç¬ç«åéçèå´å
ï¼2â¤Xâ¤5ï¼
ï¼2ï¼è®¾ç½®çæç©çº¿BCDåæå
¬å¼
Y = Aï¼X-5ï¼ 2 +2
?åæ ç¹å°
3/2 = AÃ4 +2
= -1 / 8
Y = -1 / 8ï¼5ï¼2 +2 = -1/8x 2 5/4åå
«åä¹ä¹
令为y = 0
-1/8x 2 5/4å-9/8 = 0
Ã2 10Ã9 = 0
ï¼x-1çï¼ï¼Ã-9ï¼= 0
= 1æx = 9
æ以ç¹çåæ Dï¼9,0ï¼
åæ°xèå´5â¤Xâ¤9
ï¼3ï¼æ°´å¹³è·ç¦»= OD-PA | = | 9-2 | = 7
ä¸ä¸å®ç¬¦åä¿¡æ¯ï¼ä¸ä»
è¦å¦ä¹ ï¼ç¥ä½ å¦ä¹ è¿æ¥ï¼éè¦å¨æ
é¿å°æ³
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