七年级上册数学课本上107——108页习题3.4答案
\u4e03\u5e74\u7ea7\u4e0a\u518c\u6570\u5b66\u4e66106\u9875,107\u9875\u548c108\u9875\u7684\u4e60\u98983. 4(7\u9898)\u6211\u53ea\u77e5\u9053\u4e22\u756a\u56fe\u7684\u7b54\u6848\uff0c\u522b\u4eba\u7684\u7b54\u6848\u90fd\u662f\u4e00\u4e32\u5206\u6570\u4ece\u4e0a\u5230\u4e0b\u7684\uff0c\u6211\u7684\u662f\u6bd4\u8f83\u201d\u4eba\u6027\u5316\u201c\u7684\uff0c\u6c42\u8d5e\u540c
\u89e3\uff1ax-[(1\u00f76\uff09x+\uff081\u00f712\uff09x+\uff081\u00f77\uff09x+5+\uff081\u00f72\uff09x+4] =0
x-[1/6x+1/12x+1/7x+5+0.5x+4]=0
x-[25/28x+5+4]=0
x-25/28x-9=0
x-25/28x=9
3/28x=9
x=84
\u7b54\uff1a\u7531\u6b64\u53ef\u77e5\u4e22\u756a\u56fe\u6d3b\u4e8684\u5c81\u3002
2.\u4e22\u756a\u56fe\u5f00\u59cb\u5f53\u7238\u7238\u7684\u5e74\u9f84\uff1a
84\u00d7\uff081\u00f76+1\u00f712+1\u00f77\uff09+5=38\uff08\u5c81\uff09
\u7b54\uff1a\u4e22\u756a\u56fe\u5f00\u59cb\u5f53\u7238\u7238\u7684\u5e74\u9f84\u4e3a38\u5c81\u3002
3.\u513f\u5b50\u6b7b\u65f6\u4e22\u756a\u56fe\u7684\u5e74\u9f84\uff1a
84-4=80\uff08\u5c81\uff09
\u7b54\uff1a\u513f\u5b50\u6b7b\u65f6\u4e22\u756a\u56fe\u7684\u5e74\u9f84\u4e3a80\u5c81\u3002
\u5177\u4f53\u7b54\u6848\u6765\u8fd9\u770bhttp://www.docin.com/p-43907390.html\u63d0\u793a\uff1a\u8fd9\u91cc\u76843.4\u4e60\u9898\u90e8\u5206\u662f\u7565\u7684\uff0c\u81ea\u5df1\u5bf9\u7740\u9898\u627e\u5427\uff0c\u8fde\u9898\u53f7\u90fd\u4e0d\u5bf9\uff0c\u4f46\u662f\u7b54\u6848\u5168\u5bf9
2.\u89e3\uff1a\u8bbe\u7528X\u7acb\u65b9\u7c73\u505a\u684c\u9762\uff0c\u5219\u7528(12-X)\u5e73\u65b9\u7c73\u505a\u684c\u811a\uff0c
4\u4e5820X=400(12-X)\uff0c
80x=4800-400x
420x=4800
X=10
12-X=2
\u7b54\uff1a\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002
3.\u89e3\uff1a\u8bbeX\u5929\u5236\u9020\u7532\u96f6\u4ef6\uff0c\u5219(30-X)\u5929\u5236\u4f5c\u4e59\u96f6\u4ef6\uff0c
500X=250(30-X)
500x=7500-250x
750x=7500
X=10
30-X=20
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4.\u89e3\uff1a\u8bbe\u5171\u9700X\u5c0f\u65f6
1/7.5+1/5+x/5=1
1/3+x/5=1
15(1/3+x/5)=1
5+3x=15
3x=10
x=10/3
10/3+1=13/3
\u7b54\uff1a\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002\u3002
5.\u89e3\uff1a\u8bbe\u5148\u7531x\u4eba\u505a\u4e862\u4e2a\u5c0f\u65f6\uff0c\u518d\u7531x+5\u4eba\u505a\u4e868\u5c0f\u65f6
2x+8(x+5)=80\u00d73/4
2x+8x+40=60
10x=20
x=2
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