初二数学，解方程：
\u521d\u4e8c\u6570\u5b66\u89e3\u65b9\u7a0b\u662f\u51e0\u4e2a\u9898\u5417\uff1f
\uff081\uff09x²-2x=9999 x² -2x+1=10000=(100)² (x-1)²=(100)² x=101\u6216-99
(2)\u540c\u65f6\u6269\u59273\u500d x² -2x+2=0 x\u65e0\u89e3
\uff083\uff09\uff082-\u221a3\uff09x²-2\u221a3x=2+\u221a3 [ (2-\u221a3 )x-\u221a3-2](x+1)=0 x=-1 \u6216x=1
(4)(\u221a5-\u221a2)x=3\u221a2 x=2+\u221a10
(5)\u221a2x-\u221a3y=1 \u2460 \u221a3x-\u221a2y=\u221a2 \u2461
\u2460\u00d7\u221a3\u5f97 \u221a6x-3y=\u221a3 \u2462
\u2461 \u00d7\u221a2\u5f97 \u221a6x-2y=2 \u2463
\u2463-\u2462 y=2-\u221a3 \u2464
\u628a\u2464\u4ee3\u5165\u2463\u5f97 \u221a6x-2\u00d7( 2-\u221a3)=2 \u5373 x=\u221a6-\u221a2
\u4eb2\uff0c\u8fd9\u79cd\u9898\u5728\u6c42\u89e3\u7b54\u4e0a\u4e00\u641c\u5c31\u51fa\u6765\uff0c\u5927\u5bb6\u90fd\u5728\u7528\uff0c\u8d76\u7d27\u6233\u8fdb\u53bb\u5427\uff0c\u4e0d\u7136\u5c31out\u4e86
\u4ee5\u540e\u6709\u4ec0\u4e48\u4e0d\u4f1a\u7684\u9898\uff0c\u5feb\u53bb\u201c\u6c42\u89e3\u7b54\u201d\u5427\uff0c\u4e0a\u9762\u9898\u5e93\u91cf\u8d85\u5927\uff0c\u57fa\u672c\u4e0a\u4e0d\u4f1a\u7684\u9898\u76ee\u90fd\u641c\u7684\u5230\uff0c\u6570\u5b66\u7269\u7406\u5316\u5b66\u90fd\u6709\uff0c\u5c24\u5176\u662f\u5386\u5e74\u4e2d\u8003\u9898\uff0c\u6a21\u62df\u9898\uff0c\u8bfe\u672c\u4e0a\u9898\uff0c\u800c\u4e14\u7b54\u6848\u975e\u5e38\u8be6\u7ec6\uff0c\u6ca1\u6709\u539f\u9898\u4e5f\u6709\u540c\u7c7b\u9898\uff0c\u754c\u9762\u5f88\u79d1\u5b66\u54e6\uff0c\u52a0\u6cb9\u5427
\u8fd8\u6709\u6c42\u89e3\u7b54\u9ad8\u4e2d\u7248\u6700\u8fd1\u4e5f\u4e0a\u7ebf\u4e86\uff0c\u5404\u79cd\u9ad8\u4e2d\u6570\u7406\u5316\u9898\u76ee\u7b49\u4f60\u6765\u641c\u89e3\u96be\u9898\u5c31\u53bb\u3010\u6c42\u89e3\u7b54\u3011\uff0c\u521d\u4e2d\u6570\u7406\u5316\u751f\u7269\u9898\uff0c\u9ad8\u4e2d\u6570\u7406\u5316\u751f\u7269\u9898\uff0c\u5565\u90fd\u6709
1/(x²+x)+1/(x²+3x+2)+1/(x²+5x+6)+1/(x²+7x+12)=4/21
1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)=4/21
1/x - 1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x+4)=4/21
1/x-1/(x+4)=4/21
4/(x²+4x)=4/21
x²+4x=21
x²+4x-21=0
(x+7)(x-3)=0
x1=-7 x2=3
分母先因式分解：
1/[x(x+1)]+1/[(x+1)(x+2)]+1/[(x+2)(x+3)]+1/[(x+3)(x+4)]=4/21
再拆分：
1/x-1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x+4)=4/21
合并：1/x-1/(x+4)=4/21
去分母：21(x+4-x)=4x(x+4)
x^2+4x-21=0
(x-3)(x+7)=0
得x=3或x=-7
经检验，只有x=-7为原方程的解。
绛旓細鍥炵瓟锛歺=2,y=3,z=7 璁緓=2t,鐢卞凡鐭ユ瘮渚嬪叧绯诲彲鐭,y=3t銆亃=7t, 浠ｅ叆鍒2x-8y+3z=1閲岄潰鏈4t-24t+21t=1,瑙寰梩=1,鏁厁=2,y=3,z=7銆
绛旓細瑙ｅ垎寮鏂圭▼闇瑕佷弗瀵嗙殑閫昏緫鎬濈淮鍜屼唬鏁版妧宸э紝閫愭绉疮缁忛獙锛岄愭笎鎺屾彙瑙ｉ鏂规硶銆傞櫎浜嗕互涓婄殑缁冧範棰橈紝浣犺繕鍙互鍦ㄨ鏈佺粌涔犲唽銆佸湪绾鏁板瀛︿範骞冲彴绛夊鏂归潰瀵绘壘鏇村鐨勫垎寮忔柟绋嬮鐩紝涓嶆柇缁冧範鍜屾帰绱紝鎻愰珮瑙ｉ鑳藉姏銆傚悓鏃讹紝濡傛灉閬囧埌鍥伴毦鎴栦笉鐞嗚В鐨勫湴鏂癸紝鍙婃椂鍚戣佸笀銆佸悓瀛︽垨瀹堕暱瀵绘眰甯姪锛屽叡鍚岃В鍐抽棶棰橈紝鎻愬崌鏁板姘村钩銆
绛旓細y²锛2y锛5y锛10,y^2-2y-5y+10=0,y^2-7y+10=0,(y-2)(y-5)=0 y1=2,y2=5 2x²锛8x锛1 2x^2+8x-1=0,a=2,b=8,c=-1,b^2-4ac=64+8=72 x=(-8卤鈭72)/4=(-4卤3鈭2)/2 x1=(-4+3鈭2)/2,x2=(-4-3鈭2)/2 5m²锛17m锛14锛0 (5m-7)...
绛旓細瑙ｏ細1/(x²+x)+1/(x²+3x+2)+1/(x²+5x+6)+1/(x²+7x+12)=4/21 1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)=4/21 1/x - 1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x+4)=4/21 1/x-...
绛旓細(4x锛1锛²锛3锛堝紑骞虫柟娉曪級4x+1=卤鈭3,4x=-1卤鈭3,x1=(-1+鈭3)/4.x2=(-1-鈭3)/4 3x²锛5x锛2锛0锛堝洜寮忓垎瑙ｆ硶锛(3x+1)(x-2)=0,x1=-1/3,x2=2 x²锛12x锛3锛堥厤鏂规硶锛墄^2-2*6x+36=3+36,(x-3)^2=39 x-3=卤鈭39 x=3卤鈭39,x1=3+鈭39,...
绛旓細鏈枃灏嗕负澶у浠嬬粛鍒濅腑鏁板瑙ｆ柟绋鐨勭浉鍏崇煡璇,甯姪澶у鏇村ソ鍦版帉鎻¤В鏂圭▼鐨勬柟娉曘瑙ｆ柟绋嬪熀纭瑙ｆ柟绋嬫槸鏁板涓殑涓绉嶅熀鏈繍绠,閫氳繃绛夊紡涓よ竟鐨勫彉褰,姹傚嚭鏈煡鏁扮殑鍊笺瑙ｆ柟绋嬫楠よВ鏂圭▼鐨勬楠ゅ寘鎷:鍘绘嫭鍙枫佸悎骞跺悓绫婚」銆佺Щ椤广佸寲绠銆佹眰瑙ｃ瑙ｆ柟绋嬪疄渚嬩緥濡:20=5+3脳5;30=5+5脳5;40=19+3脳7鎴40=7+3脳11;...
绛旓細鍦ㄨВ棰樿繃绋嬩腑,鎴戜滑浣跨敤浜嗚繍绠楁硶鍒欏皢鏂圭▼绠鍖栦负鏇村鏄撹绠楃殑褰㈠紡銆傝繖绉嶆柟娉曞彲浠ュ府鍔╂垜浠洿濂藉湴鐞嗚В闂骞惰В鍐虫柟绋嬨 3. 瀛ょ珛鍙橀噺: 瑙ｆ柟绋嬬殑鍏抽敭姝ラ鏄皢鏈煡鏁板绔嬪嚭鏉,浣垮緱鏂圭▼涓彧鍓╀笅涓涓湭鐭ユ暟銆傞氳繃杩涜閫嗚繍绠楀拰绛夊紡鎬ц川鐨勫簲鐢,鎴戜滑鍙互鏈夋晥鍦姹傝В鏂圭▼涓殑鏈煡鏁般 鎺屾彙瑙ｆ柟绋嬬殑鎶宸у拰鏂规硶鏄鏁板瀛︿範鐨勯噸瑕佸唴瀹,...
绛旓細2X²=8 X²=4 X=2 2. 锛2x-1)³=-8 2X-1=-2 X=-0.5 甯屾湜鍙互甯埌浣
绛旓細瑙ｏ細鏂圭▼涓よ竟鍚屾椂涔樹互2锛3+x)锛屽緱 2锛2 鈥攛)绛変簬锛坸+3锛+2 瑙ｈ繖涓笉绛夊紡锛屽緱 x绛変簬-3/1 妫楠岋細灏唜绛変簬-3/1浠ｅ叆鍘鏂圭▼锛寰 宸﹁竟绛変簬-3/1绛変簬鍙宠竟 鎵浠ワ細x绛変簬-3/1灏辨槸鍘熸柟绋嬬殑鏍
绛旓細(68+x)脳3.5=455瑙ｆ柟绋嬪紡杩囩▼濡備笅锛(68+x)脳3.5=455 瑙ｏ細68+x=130 x=130-68 x=62 鎵浠(68+x)脳3.5=455瑙ｆ柟绋嬪紡鏈鍚庣殑缁撴灉鏄痻=62銆
