初一数学代数式求值1 初一数学代数式求值题
\u521d\u4e00\u6570\u5b66\u4ee3\u6570\u5f0f\u6c42\u503c\uff0c\u5df2\u77e51/x+1/y=2\uff0c\u6c42(2x+5xy+2y)/(-x+3xy-y)\u75311/y+1/x=2\u65b9\u7a0b\u4e24\u8fb9\u540c\u65f6\u4e58\u4ee5xy\u5f97y+x=2xy\u2460
\u7531(2x+5xy+2y)/(-x+3xy-y)\u5206\u5b50\u5206\u6bcd\u5206\u522b\u5408\u5e76\u5f97[2\uff08x+y\uff09+5xy]/[-(x+y)+3xy]\u2461
\u628a\u2460\u4ee3\u5165\u2461\u5f97(4xy+5xy)/(-2xy+3xy)=9xy/xy=9
\u5e0c\u671b\u4f60\u6ee1\u610f......
3ab-4ab+8ab-7ab+ab=______\uff0e
4\uff0e7x-(5x-5y)-y=______\uff0e
5\uff0e23a3bc2-15ab2c+8abc-24a3bc2-8abc=______\uff0e
6\uff0e-7x2+6x+13x2-4x-5x2=______\uff0e
7\uff0e2y+(-2y+5)-(3y+2)\uff1d______\uff0e
11\uff0e(2x2-3xy+4y2)+(x2+2xy-3y2)=______\uff0e
12\uff0e2a-(3a-2b+2)+(3a-4b-1)=______\uff0e
13\uff0e-6x2-7x2+15x2-2x2\uff1d______\uff0e
14\uff0e2x-(x+3y)-(-x-y)-(x-y)\uff1d______\uff0e
16\uff0e2x+2y-[3x-2(x-y)]=______\uff0e
17\uff0e5-(1-x)-1-(x-1)=______\uff0e
18\uff0e( )+(4xy+7x2-y2)=10x2-xy\uff0e
19\uff0e(4xy2-2x2y)-( )=x3-2x2y+4xy2+y3\uff0e
21\uff0e\u5df2\u77e5A=x3-2x2+x-4\uff0cB=2x3-5x+3\uff0c\u8ba1\u7b97A+B=______\uff0e
22\uff0e\u5df2\u77e5A=x3-2x2+x-4\uff0cB=2x3-5x+3\uff0c\u8ba1\u7b97A-B=______\uff0e
23\uff0e\u82e5a=-0.2\uff0cb=0.5\uff0c\u4ee3\u6570\u5f0f-(|a2b|-|ab2|)\u7684\u503c\u4e3a______\uff0e
25\uff0e\u4e00\u4e2a\u591a\u9879\u5f0f\u51cf\u53bb3m4-m3-2m+5\u5f97-2m4-3m3-2m2-1\uff0c\u90a3\u4e48\u8fd9\u4e2a\u591a\u9879\u5f0f\u7b49\u4e8e______\uff0e
26\uff0e-(2x2-y2)-[2y2-(x2+2xy)]=______\uff0e
27\uff0e\u82e5-3a3b2\u4e0e5ax-1by+2\u662f\u540c\u7c7b\u9879\uff0c\u5219x=______\uff0cy=______\uff0e
28\uff0e(-y+6+3y4-y3)-(2y2-3y3+y4-7)\uff1d______\uff0e
29\uff0e\u5316\u7b80\u4ee3\u6570\u5f0f4x2-[7x2-5x-3(1-2x+x2)]\u7684\u7ed3\u679c\u662f______\uff0e
30\uff0e2a-b2+c-d3=2a+( )-d3=2a-d3-( )=c-( )\uff0e
31\uff0e3a-(2a-3b)+3(a-2b)-b=______\uff0e
32\uff0e\u5316\u7b80\u4ee3\u6570\u5f0fx-[y-2x-(x+y)]\u7b49\u4e8e______\uff0e
33\uff0e[5a2+( )a-7]+[( )a2-4a+( )]=a2+2a+1\uff0e
34\uff0e3x-[y-(2x+y)]=______\uff0e
35\uff0e\u5316\u7b80|1-x+y|-|x-y|(\u5176\u4e2dx\uff1c0\uff0cy\uff1e0)\u7b49\u4e8e______\uff0e
36\uff0e\u5df2\u77e5x\u2264y\uff0cx+y-|x-y|=______\uff0e
37\uff0e\u5df2\u77e5x\uff1c0\uff0cy\uff1c0\uff0c\u5316\u7b80|x+y|-|5-x-y|=______\uff0e
38\uff0e4a2n-an-(3an-2a2n)\uff1d______\uff0e
39\uff0e\u82e5\u4e00\u4e2a\u591a\u9879\u5f0f\u52a0\u4e0a-3x2y+2x2-3xy-4\u5f97
2x2y+3xy2-x2+2xy\uff0c
\u5219\u8fd9\u4e2a\u591a\u9879\u5f0f\u4e3a______\uff0e
40\uff0e-5xm-xm-(-7xm)+(-3xm)=______\uff0e
41\uff0e\u5f53a=-1\uff0cb=-2\u65f6\uff0c
[a-(b-c)]-[-b-(-c-a)]\uff1d______\uff0e
43\uff0e\u5f53a=-1\uff0cb=1\uff0cc=-1\u65f6\uff0c
-[b-2(-5a)]-(-3b+5c)\uff1d______\uff0e
44\uff0e-2(3x+z)-(-6x)+(-5y+3z)=______\uff0e
45\uff0e-5an-an+1-(-7an+1)+(-3an)\uff1d______\uff0e
46\uff0e3a-(2a-4b-6c)+3(-2c+2b)=______\uff0e
48\uff0e9a2+[7a2-2a-(-a2+3a)]=______\uff0e
50\uff0e\u5f532y-x=5\u65f6\uff0c5(x-2y)2-3(-x+2y)-100=______\uff0e
4a+8a-(-6a)+3a-2b
8a+4(a+2)
(2n-3)+(2n+3)-(2n-3)
7x-(5x-5y)-y
3a-4b+4a-3b
7a+3b-(4a+5b)-3
3ab-4ab+8ab-7ab+ab
(x-y)-2(x-y)
.16m+25-40m+34m
.(4+2x)+(2x-x)
4a+8a-(-6a)+3a-2b
.8a+4(a+2)
(2n-3)+(2n+3)-(2n-3)
7x-(5x-5y)-y
3a-4b+4a-3b
一般先化简，再求值。
绛旓細(4+2x)+(2x-x)4a+8a-(-6a)+3a-2b 8a+4(a+2)(2n-3)+(2n+3)-(2n-3)7x-(5x-5y)-y 3a-4b+4a-3b 7a+3b-(4a+5b)-3 3ab-4ab+8ab-7ab+ab (x-y)-2(x-y).16m+25-40m+34m .(4+2x)+(2x-x)4a+8a-(-6a)+3a-2b .8a+4(a+2)(2n-3)+(2n+3)-(2n-3)7x...
绛旓細1,=(1+5)m²-3m²+4m+5m+2=2m²+9m+2=17\4 2,=-2a²b²-4ab=3鍙1\2 3锛=x+y-z-2x+y-3x+3y-3z=-4x+5y-6z=13.5
绛旓細銆愯В绛斻戣В锛氬綋x=1鏃讹紝鍘熷紡=4锕3=1锛屾晠閫堿.銆愮偣璇勩戞棰樿冩煡浜浠ｆ暟寮忔眰鍊锛岀啛缁冩帉鎻¤繍绠楁硶鍒欐槸瑙ｆ湰棰樼殑鍏抽敭.6.宸茬煡x=1锛寉=2锛屽垯浠ｆ暟寮弜锕鐨勫间负()A.1 B.锕1 C.2 D.锕3 銆愯冪偣銆戜唬鏁板紡姹傚.銆愬垎鏋愩戞牴鎹唬鏁板紡鐨勬眰鍊 鏂规硶 锛屾妸x=1锛寉=2浠ｅ叆x锕锛屾眰鍑轰唬鏁板紡x锕鐨勫间负...
绛旓細(1)灏唜=0浠ｅ叆寰0+0+0+c=-1 鎵浠=-1 (2)浠ｅ叆寰梐+b+3+c=-1 绉婚」寰梐+b+c=-1-3=-4 (3)x=3浠ｅ叆寰 243a+27b+9-1=9鎵浠243a+27b=1 褰搙=-3鏃 鍘熷紡=-243a-27b-9-1 =-(243a+27b)-10 =-1-10 =-11
绛旓細浠ｆ暟寮 : 1.鏈夌悊寮 锛2.鏁村紡 锛3.澶氶」寮 锛4.鍗曢」寮 锛5.鍒嗗紡 锛6.鏃犵悊寮 浠ｆ暟寮忓湪瀹炴暟鑼冨洿鍐,浠ｆ暟寮忓垎涓烘湁鐞嗗紡鍜屾棤鐞嗗紡銆
绛旓細瑙ｏ細渚濋鎰忔湁|m+2|>=0,(n-1)²>=0 鍒欐湁m+2=0锛宯-1=0锛屽緱m=-2锛宯=1锛屾晠m+2n=0
绛旓細(1)鍒楀嚭浠ｆ暟寮:鐢ㄦ嫭鍙锋妸姣忎釜鏁村紡鎷捣鏉,鍐嶇敤鍔犲噺鍙疯繛鎺ャ (2)鎸夊幓鎷彿娉曞垯鍘绘嫭鍙枫 (3)鍚堝苟鍚岀被椤广 4銆浠ｆ暟寮忔眰鍊鐨勪竴鑸楠: (1)浠ｆ暟寮忓寲绠 (2)浠ｅ叆璁＄畻 (3)瀵逛簬鏌愪簺鐗规畩鐨勪唬鏁板紡,鍙噰鐢ㄢ滄暣浣撲唬鍏モ濊繘琛岃绠椼 浜烘暀鐗涓冨勾绾涓婂唽鏁板鐭ヨ瘑2 鍥惧舰鐨勫垵姝ヨ璇 涓銆佺珛浣撳浘褰笌骞抽潰鍥惧舰 1銆侀暱鏂逛綋銆佹鏂逛綋...
绛旓細灏嗕笅鍒楀悇寮忓厛鍖栫畝锛屽啀姹傚 1锛庡凡鐭+b=2锛宎-b=-1锛屾眰3(a+b)2(a-b)2-5(a+b)2脳(a-b)2鐨勫硷紟2锛庡凡鐭=a2+2b2-3c2锛孊=-b2-2c2+3a2锛孋=c2+2a2-3b2锛屾眰(A-B)+C锛3锛庢眰(3x2y-2xy2)-(xy2-2x2y)锛屽叾涓瓁=-1锛寉=2锛4锛庡凡鐭x+1|+(y-2)2=0锛屾眰浠ｆ暟寮5(2x-y)...
绛旓細鐢1/y+1/x=2鏂圭▼涓よ竟鍚屾椂涔樹互xy寰梱+x=2xy鈶 鐢(2x+5xy+2y)/(-x+3xy-y)鍒嗗瓙鍒嗘瘝鍒嗗埆鍚堝苟寰梉2锛坸+y锛+5xy]/[-(x+y)+3xy]鈶 鎶娾憼浠ｅ叆鈶″緱(4xy+5xy)/(-2xy+3xy)=9xy/xy=9 甯屾湜浣犳弧鎰...
绛旓細1/x-1/y=3 閫氬垎 (y-x)/xy=3 y-x=3xy x-y=-3xy 鍘熷紡=[2(x-y)-14xy]/[(x-y)-2xy]=[2(-3xy)-14xy]/[(-3xy)-2xy]=-20xy/(-5xy)=4
