一道七年级数学题~关于代数式的！谢谢了！
\u4e03\u5e74\u7ea7\u6570\u5b66\u9898 \u4ee3\u6570\u5f0f\u56e0\u4e3aa=m+xc,b=n+yc,\u4e24\u5f0f\u76f8\u52a0\u5f97\uff1aa+b=m+n+(x+y)c \u7531\u4e8em+n=(a+b)/2\uff0c\u5e26\u5165\u4e0a\u5f0f\u6709m+n=(x+y)c \u56e0\u4e3am+n<2c,\u5373(x+y)c<2c,\u5373x+y<2 \u5f53x+y=0\u65f6\uff0c\u5373a=m\uff0cb=n\uff0c\u4e0em+n=(a+b)/2\u77db\u76fe\uff0c\u4e0d\u7b26\u5408 \u5219\u53ea\u6709X+Y=1\uff0c\u5373m+n=c
\u91c7\u7eb3\u6211\u5427\u8c22\u8c22
1\u3001\u4e00\u9879\u5de5\u7a0b\uff0ca\u4e2a\u4ebam\u5929\u53ef\u4ee5\u5b8c\u6210\uff0c\u5982\u679c\u589e\u52a0b\u4e2a\u4eba\uff08\u5047\u8bbe\u6bcf\u4e2a\u4eba\u6548\u7387\u76f8\u540c\uff09\uff0c\u9700\u8981\u591a\u5c11\u5929\uff1f\uff08\u7528\u4ee3\u6570\u5f0f\u8868\u793a\uff0c\u4e0d\u5199\u8fc7\u7a0b\uff0c\u76f4\u63a5\u5199\u7b54\u6848\uff01\uff09
2\u3001\u4e00\u79cd\u5546\u54c1\u539f\u4ef7a\u5143\uff0c\u7ecf\u8fc7\u4e24\u6b21\u4ef7\u683c\u4e0b\u8c03\uff0c\u6bcf\u6b21\u4e0b\u8c035%\uff0c\u4e0b\u8c03\u540e\u4ef7\u683c\u4e3a\u591a\u5c11\uff1f\uff08\u540c\u4e0a\uff09
3\u3001\u82e5A=x-5y\uff0cB=y+5X\uff0c\u52192A-3B=\uff1f\uff08\u540c\u4e0a\uff0c\u76f4\u63a5\u5199\u7b54\u6848\uff09
4\u3001A\u3001B\u4e24\u5730\u76f8\u8dddS\u5343\u7c73\uff0c\u7532\u3001\u4e59\u4e24\u8f86\u6c7d\u8f66\u5206\u522b\u4eceA\u3001B\u4e24\u5730\u540c\u65f6\u5f00\u51fa\uff0c\u76f8\u5411\u800c\u884c\uff0ct\u5c0f\u65f6\u76f8\u9047\uff0c\u5df2\u77e5V\u7532=a km\h\uff0cV\u4e59=b km\h\uff0c\u7528a\u3001b\u7684\u4ee3\u6570\u5f0f\u8868\u793as\uff0c\u5e76\u8ba1\u7b97t=2.4\uff0ca=70.b=80\u65f6\uff0cs\u7684\u503c\uff08\u5199\u8fc7\u7a0b\uff0c\u8981\u8be6\u7ec6\uff09
1\u3001am/(a+b)\uff1b
2\u3001a(1-5%)²\uff1b
3\u3001-13x-13y\uff1b
4\u3001S=(a+b)*t \uff1b
t=2.4\uff0ca=70.b=80\u65f6\uff0cS=360\u5343\u7c73\uff1b
= 3 x 5 - 11
= 15 - 11
= 4
等于0
因为 2*a*a+3*a+1=5
所以 3*(2*a*a＋3a＋1)=3*5=15
所以 6*a*a+9*a+3=15
所以 6*a*a+9*a+3-11=15-11=4
所以 6*a*a+9*a-8=4
绛旓細m-n=1-(-5)=6
绛旓細1-4=-3锛庢晠绛旀涓猴細-1锛1锛5锛岋紙2锛-3,(3) 鐢遍鎰忥紝寰1锛渒锛5锛屸埓鍘熷紡=k-1-2锛坘+1锛+锛5-k锛夛紝=k-1-2k-2+5-k锛=-2k+2锛
绛旓細2銆丄-2B==5xy+2y-2x=(5y-2)x+2y 鐢遍鎰忓彲寰楋細5y-2=0锛岃В寰梱=2/5
绛旓細6a²锛9a锛8 = 3 (2a²锛3a锛1)- 3 - 8 = 3 x 5 - 11 = 15 - 11 = 4
绛旓細1銆2A-B=4a²-2a-锛-a²-a锛=4a²-2a+a²+a=5a²-a 2銆佸 3銆5-a+3b=5-锛坅-3b锛=5-锛-3锛=8 4銆丅锛屾暣寮忎腑闄ゆ暟涓嶈兘鍚湁瀛楁瘝 5銆4锛-1,2锛屽崟锛-5/7 6銆丄-2B=2x²+3xy+2x-1-2x²-2xy-6x+4=xy-4x+3 涓嶺鏃犲叧锛屽嵆寰楀嚭鐨勫紡瀛...
绛旓細鍒嗘瀽:鏍规嵁棰樻剰鍙埄鐢ㄢ滄暣浣撲唬鍏ユ硶鈥濇妸x锕2y=锕2浠ｅ叆浠ｆ暟寮,鐩存帴姹傚嚭浠ｆ暟寮忕殑鍊.瑙ｇ瓟:瑙:鈭祒锕2y=锕2,鈭3锕+2y=3锕(x锕2y)=3锕(锕2)=5,鏁呴塂.鐐硅瘎:鏈鏃㈣冩煡浜嗘暣浣撶殑鏁板鎬濇兂,鍚屾椂杩橀殣鍚簡姝ｇ‘杩愮畻鐨勮兘鍔,姣旇緝绠鍗.7.(2011骞夸笢鐝犳捣,2,3鍒)鍖栫畝(a3)2鐨勭粨鏋滄槸 ( ) A. a6 B.a5 C.a9 D...
绛旓細11銆佹煇鏍″幓骞鍒濅竴鎷涙敹鏂扮敓x浜猴紝浠婂勾姣斿幓骞村鍔20%,鐢浠ｆ暟寮琛ㄧず浠婂勾璇ユ牎瀛︾敓浜烘暟涓 銆12銆佷竴涓叉湁榛戞湁鐧斤紝鍏舵帓鍒楁湁涓瀹氳寰嬬殑鐝犲瓙锛岃鐩掑瓙閬綇涓閮ㄥ垎 锛堝鍙冲浘锛夛紝鍒欒繖涓茬彔瀛愯鐩掑瓙閬綇鐨勯儴鍒嗘湁___棰椼備簩銆佸紑蹇冮変竴閫夛紙姣忛2鍒嗭紝鍏12鍒嗭級13銆 |锛2|鐨勭浉鍙嶆暟鏄紙 锛堿锛庯紞 B锛 锛2...
绛旓細绛旓細x=1鏃讹紝px³+qx+1=2001 p+q+1=2001 p+q=2000 x=-1鏃讹細px³+qx+1 =-p-q+1 =-2000+1 =-1999 鎵浠ワ細褰搙=1鏃,浠ｆ暟寮px鐨勪笁娆℃柟+qx+1鐨勫兼槸2001,鍒欏綋x=-1鏃,浠ｆ暟寮弍x鐨勪笁娆℃柟+qx+1鐨勫兼槸-1999
绛旓細瑙ｏ細5x^2-(3xy+4y^2)-(11xy-2y^2)-7x^2 =5x^2-3xy-4y^2-11xy+2y^2-7x^2 =-2x^2-14xy-2y^2 =-2(x^2+7xy+y^2)鍥犱负 x^2+y^2=7 xy=-1 鎵浠 -2(x^2+7xy+y^2)=-2 脳锛7-7锛=0
绛旓細姹備笅鍒浠ｆ暟寮忕殑鍊硷細 绗竴棰橈細4x鐨勫钩鏂-3x鐨3娆℃柟-x-4+2x鐨3娆℃柟+3x+x鐨3娆℃柟+9,鍏朵腑x=涓鍙堜簩鍒嗕箣涓 绗簩棰橈細a鐨3娆℃柟-a鐨勫钩鏂筨+ab鐨勫钩鏂+a鐨勫钩鏂筨-ab鐨勫钩鏂+b鐨3娆℃柟,鍏朵腑a=1,b=-3 绗笁棰橈細3锛坅-b锛夌殑骞虫柟-9锛坅-b锛-2锛坅-b锛夌殑骞虫柟+5锛坅-b锛,鍏朵腑a-b=2 4x鐨勫钩鏂-...
