初二数学，第八题...讲解一下更好
\u521d\u4e8c\u6570\u5b66\u9898\uff0c\u6c42\u8be6\u89e3\uff0c\u8c22\u8c22\uff011.(1)\u76f4\u7ebf\u4e0ey\u8f74\u4ea4\u70b9\u4e3a(0,-(m-2))\uff0c\u6545-(m-2)>0(\u5373m<2)\u65f6\uff0c\u76f4\u7ebf\u4e0ey\u8f74\u7684\u4ea4\u70b9\u5728x\u8f74\u4e0a\u65b9\u3002
(2)\u7531\u76f4\u7ebf\u7ecf\u8fc7\u7b2c\u4e00\u3001\u4e09\u3001\u56db\u8c61\u9650\uff0c\u77e5\uff1a
4m-1>0
-(m-2)<0
\u7efc\u4e0a\uff0cm>2\u3002
(3)\u76f4\u7ebf\u4e0d\u7ecf\u8fc7\u7b2c\u4e8c\u8c61\u9650\uff0c\u6545
4m-1>=0
-(m-2)<=0
\u7efc\u4e0a\uff0cm>=2
2.(1)\u8bbey-4=kx
\u5373y=kx+4
\u7531x=6,y=-4\u89e3\u5f97k=-4/3
(2)\u8bbep\u70b9\u5750\u6807\u4e3a(0,a)
\u7531\u9898\u77e5\uff1a
S=(4-a)*3*1/2=9
\u89e3\u5f97a=-2
\u5373P(0,-2)
\u65b9\u7a0b\u7684Y\u5728\u54ea\uff1f
绛旓細瑙ｏ細鈭礎BCD鏄钩琛屽洓杈瑰舰 鈭碆O=OD锛堝瑙掔嚎鐩镐簰骞冲垎锛変笖AB=CD锛孉D=BC 鈭礎BCD鍛ㄩ暱=AB+CD+AD+BC=36 鈭碆C+CD=AB+AD=18 鈭礒鏄疌D鐨勪腑鐐癸紝O鏄疊D鐨勪腑鐐 鈭碠E鏄柍DBC鐨勪腑浣嶇嚎 鈭碠E=BC/2 鑰孌E=CD/2 鈭碠E+DE=锛圔C+CD锛/2 =18/2=9 鑰孫D=BD/2=6 鈭粹柍ODE鐨勫懆闀=OD+OE+ED=9+6=15 ...
绛旓細鏍规嵁涓夎褰㈢殑鐩镐技鎬х煡锛屾瘡涓涓繖鏍疯繛鎺ュ緱鍒扮殑涓夎褰笌鍓嶄竴涓殑鐩镐技姣斾负1/2 閭ｄ箞锛屽叾闈㈢Н姣斿氨鏄(1/2)²=1/4 宸茬煡S鈻矨BC=8 鍒欙紝S1=8*(1/4)锛汼2=[8*(1/4)]*(1/4)=8*(1/4)²锛屸︹﹂偅涔锛岀100涓殑闈㈢НS100=8*[(1/4)^100]=2³*[(1/2)^200]=1/(2^197...
绛旓細8.璇佹槑:鍦ˋB涓婃埅鍙朅M=AF,杩炴帴DM.鈭礎M=AF,鈭燤AD=鈭燜AD,AD=AD.鈭粹娍MAD鈮屸娍FAD(SAS),DM=DF;鈭2=鈭1.鈭碘垹EDF+鈭燛AF=180掳.(宸茬煡)鈭粹垹4+鈭1=180掳.(鍥涜竟褰㈠唴瑙掑拰涓360搴)鈭粹垹4+鈭2=180掳.(绛夐噺浠ｆ崲)鍙堚埖鈭3+鈭2=180掳.(骞宠瀹氫箟)鈭粹垹3=鈭4.(鍚岃鐨勮ˉ瑙掔浉绛).鈭碊E=DM.(绛夎...
绛旓細鍥炵瓟锛氳鑷杞︾殑閫熷害鏄痻鍗冪背/灏忔椂,鍒欐苯杞﹂熷害鏄3x鍗冪背/灏忔椂渚濋鎰忓緱(24/x)−1=24/(3x), 鏂圭▼涓よ竟鍚屼箻浠3x,寰72−3x=24, 瑙ｅ緱x=16 缁忔楠,x=16鏄師鏂圭▼鐨勮В 鈭村師鏂圭▼鐨勮В涓簒=16,杩欐椂3x=48. 鈭磋嚜琛岃溅鐨勯熷害鏄16鍗冪背/灏忔椂,姹借溅閫熷害鏄48鍗冪背/灏忔椂.
绛旓細鍥犱负 ME鍨傜洿浜嶢C, DG鍨傜洿浜嶢C, 鎵浠E//DG,鎵浠ュ洓杈瑰舰DMEN鏄钩琛屽洓杈瑰舰锛堜袱缁勫杈瑰钩琛岀殑鍥涜竟褰㈡槸骞宠鍥涜竟褰級锛屽洜涓 涓夎褰BC鏄瓑鑵颁笁瑙掑舰锛 鎵浠 瑙扗BM 锛 瑙扙CM ,鍥犱负 M鏄疊C鐨勪腑鐐, 鎵浠 BM=CM,瑙払DM锛濊CEM锛90搴, 鎵浠 涓夎褰DM 鍏ㄧ瓑浜 涓夎褰EM锛孌M=EM...
绛旓細鈭碈E=BP.鈭礎B=AP+BP,鈭碅B=AE+CE.锛2锛夛細鈭礑鏄疊C涓偣锛屸埓BD=CD鈭礎D=1/2BC鈭碅D=CD銆傗埓鈻矨CD鏄瓑杈逛笁瑙掑舰锛屸埓鈭燗CD=60掳=鈭燗DC锛屸埖AD=AB鈭粹垹ABD=30掳鈭碘柍BDP鈮屸柍CED锛屸埓鈭燚CE=鈭燗BD=30掳锛屸埓鈭燗CE=鈭燗CD+鈭燚CE=60掳+30掳=90掳鈭粹柍ACE鏄洿瑙掍笁瑙掑舰銆
绛旓細瑙ｏ細鈭礑H鈯C 鈭粹垹DHA=鈭燙HD=90掳 鈭碘垹ADH=30掳 鈭碅D=2AB 璁続H=x锛屽垯AD=2x 鍦≧t鈻矨HD涓瑼H²+DH²=AD²x²+2²=锛2x锛²x=2/3鈭3 AD=4/3鈭3 鈭碘垹HDC=鈭燗DC-鈭燗DH=90掳-30掳=60掳 鍦≧t鈻矯DH涓垹HDC+鈭燚CH=90掳 鈭粹垹DCH=90掳-鈭燞DC=90...
绛旓細鍥犱负BE=CF 鎵浠E+EC=CE+EF 鎵浠C=CF 鏁呪柍ABC鍏ㄧ瓑浜庘柍DEF锛圫.S.S)鎵浠モ垹B=鈭燚EF AB鈭E 鈭燜=鈭燗CB AC鈭F
绛旓細8銆佸嶉暱涓嚎 鍐嶅埄鐢ㄤ袱杈逛箣鍜屽ぇ浜庣涓夎竟锛屼袱杈逛箣宸皬浜庣涓夎竟姹侫D鐨勮寖鍥 寤堕暱AD鍒扮偣E锛屼娇DE锛滵A锛岃繛鎺E 鍥犱负锛孌涓築C涓偣锛屽垯BD锛滳D 鍙堬紝鈭燘DE锛濃垹CDA锛堝椤惰鐩哥瓑锛塂A锛滵E 鎵浠ワ紝鈻矪ED鈮屸柍CAD 鎵浠ワ紝BE锛滱C 鈻矨BE涓紝AB锛12锛孊E锛滱C锛8 AE锛滵A锛婦E锛2AD 鍥犱负锛屼笁瑙掑舰涓紝涓よ竟涔嬪拰澶т簬...
绛旓細x^4-81=(x^2+9)(x^2-9)=(x^2+9)(x+3)(x-3) x^2-9=(x+3)(x-3) x^2-6x+9=(x-3)(x+3)鎵浠ユ槸B
