某市为了节约用水，对自来水的收费标准作如下规定：每月每户用水不超过10吨的部分，按2元/吨收费；超过10 某事为鼓励节约用水，对自来水的收费标准作如下规定：每月每户用...
\u67d0\u5e02\u4e3a\u4e86\u9f13\u52b1\u8282\u7ea6\u7528\u6c34\u5bf9\u81ea\u6765\u6c34\uff0c\u5bf9\u81ea\u6765\u6c34\u7684\u6536\u8d39\u6807\u51c6\u4f5c\u4e86\u5982\u4e0b\u89c4\u5b9a\uff1a\u6bcf\u6708\u6bcf\u6237\u7528\u6c34\u4e0d\u8d85\u8fc710\u5428\u7684\u90e8\u5206\uff0c\u63092.05\u8bbe\u674e\u8001\u5e08\u5bb6\u516d\u6708\u4efd\u7528\u6c34x\u5428\uff0c\u5047\u8bbe10\uff1cx\uff1c20\u65f6\uff0c\u5219\u56e0\u4e3a\uff1a2.05\u00d710+2.2\u00d7\uff0820-10\uff09=42.5\uff1e38.1\uff0c\u6240\u4ee5\uff1a\u674e\u8001\u5e08\u5bb6\u516d\u6708\u4efd\u7528\u6c34\u4e0d\u8d85\u8fc720\u5428\uff0c\u6839\u636e\u9898\u610f\uff0c\u8fd9x\u5428\u6c34\u4e2d\uff0c\u524d10\u5428\u6c34\u4ef7\u4e3a\uff1a2.05\u5143/\u5428\uff0c\u5269\u4e0b\u7684\uff1a\uff08x-20\uff09\u5428\u7684\u6c34\u4ef7\u4e3a2.2\u5143/\u5428\uff0c\u6545\u5217\u65b9\u7a0b\uff1a2.05\u00d710+2.2\uff08x-10\uff09=38.1\uff0e\u89e3\u5f97\uff1ax=18\uff0e\u7b54\uff1a\u674e\u8001\u5e08\u5bb6\u516d\u6708\u4efd\u7528\u6c3418\u5428\uff0e
\u67d0\u5e02\u4e3a\u9f13\u52b1\u8282\u7ea6\u7528\u6c34\uff0c\u5bf9\u81ea\u6765\u6c34\u7684\u6536\u8d39\u6807\u51c6\u4f5c\u5982\u4e0b\u89c4\u5b9a\uff1a\u6bcf\u6708\u6bcf\u6237\u7528\u6c34\u4e0d\u8d85\u8fc710\u5428\u7684\u90e8\u5206\uff0c\u63090. 45\u5143\uff0f\u5428\u6536\u8d39\uff1b\u8d85\u8fc710\u5428\u800c\u4e0d\u8d85\u8fc720\u5428\u7684\u90e8\u5206\uff0c\u63090. 80\u5143\uff0f\u5428\u6536\u8d39\uff1b\u8d85\u8fc720\u5428\u7684\u90e8\u5206\u63091. 50\u5143\uff0f\u5428\u6536\u8d39\uff0c\u67d0\u6708\u7532\u6237\u6bd4\u4e59\u6237\u591a\u7f34\u6c34\u8d397. 10\u5143\uff0c\u4e59\u6237\u6bd4\u4e19\u6237\u591a\u7f34\u6c34\u8d393. 75\u5143\u3002\u95ee\u7532\u3001\u4e59\u3001\u4e19\u8be5\u6708\u5404\u7f34\u6c34\u8d39\u591a\u5c11\u5143(\u6309\u6574\u5428\u6536\u8d39)?( )
A.16\u5143\uff0c8. 9\u5143\uff0c5. 15\u5143B.14\u5143\uff0c6. 9\u5143\uff0c3. 15\u5143C.15\u5143\uff0c7. 9\u5143\uff0c4. 15\u5143D.13\u5143\uff0c5. 9\u5143\uff0c2. 15\u5143\u7b54\u6848\uff1ab
\u89e3\u6790\uff1a\u5982\u679c\u76f4\u63a5\u8bbe\u6240\u7f34\u6c34\u8d39\u4e3a\u672b\u77e5\u6570\uff0c\u7b49\u91cf\u5173\u7cfb\u4e0d\u660e\u663e\uff0c\u5217\u65b9\u7a0b\u96be\u5ea6\u592a\u5927\uff0c\u6240\u4ee5\u53ef\u95f4\u63a5\u8bbe\u4ed6\u4eec\u7684\u7528\u6c34\u91cf\u4e3a\u672a\u77e5\u6570\u3002
\u8bbe\u4e19\u6237\u7528\u6c34\u4e3ax\u5428(x\u4e3a\u6574\u6570\uff0c\u4e14O\u2264x\u226410).\u4e59\u6237\u7528\u6c34\u4e3a(10+y)\u5428(y\u4e3a\u6574\u6570\uff0c\u4e14O\uff1cy\u226410)\uff0c\u56e0\u4e59\u6237\u6bd4\u4e19\u6237\u591a\u7f343.75\u5143\uff0c\u5219\u6709O.4x+3.75=O.80y+0.45\u00d710\uff0c\u53739x-16y=15\u3002\u56e0\u4e3a3\u80fd\u6574\u96649\u548c15\uff0c\u4f46\u4e0d\u80fd\u6574\u966416\uff0c\u65453\u5fc5\u80fd\u6574\u9664y\uff0c\u5373y\u662f3\u7684\u500d\u6570\u3002
\u53c8\u56e0\u4e3a0\u7ecf\u9a8c\u8bc1\uff0cy=3\u662f\u552f\u4e00\u80fd\u4f7fx\u4e3a\u6574\u6570\u7684\u503c\uff0c\u8fd9\u65f6x=7.
\u540c\u7406\uff0c\u8bbe\u7532\u6237\u7528\u6c34(20+z)\u5428(z\u4e3a\u6574\u6570\uff0c\u4e14z>O)\uff0c\u56e0\u7532\u6237\u6bd4\u4e59\u6237\u591a\u7f347.10\u5143\uff0c\u6709
0.80y+0.45\u00d710+7.10=1.50z+0.45\u00d710+0.80\u00d710\uff0c
\u53738y-15z=9\uff0c
\u628a\u0443=3\u4ee3\u4eba\uff0c\u5f97z=1\uff0c
\u6545\u7532\u6237\u7f34\u7eb3\u6c34\u8d39\u4e3a\uff1a1.50+0.45\u00d710+O.80x10=14(\u5143)\uff0c
\u4e59\u6237\u7f34\u7eb3\u6c34\u8d39\u4e3a\uff1aO.80\u00d73+0.45\u00d710=6.9(\u5143)\uff0c
\u4e19\u6237\u7f34\u7eb3\u6c34\u8d39\u4e3a\uff1a0.45\u00d77=3.15(\u5143)\u3002
\u540c\u7c7b\u8bd5\u9898
答：应交水费35元；
（2）设黄老师家5月份用水x吨，由题意得
10×2+2.5×（x-10）=30，
解得x=14，
答：黄老师家5月份用水14吨；
（3）①当0＜a≤10时，应交水费为2a（元），
②当a＞10时，应交水费为：20+2.5（a-10）=2.5a-5（元）．
绛旓細鏌愬競涓轰簡鑺傜害鐢ㄦ按锛屽鑷潵姘寸殑鏀惰垂鏍囧噯浣滃涓嬭瀹氾細姣忔湀姣忔埛鐢ㄦ按涓嶈秴杩10鍚ㄩ儴鍒嗭紝鎸2鍏/鍚ㄦ敹璐癸紱瓒呰繃10鍚ㄨ屼笉瓒呰繃20鍚ㄩ儴鍒嗘寜2.5/鍚ㄦ敹璐癸紱瓒呰繃20鍚ㄩ儴鍒嗭紝鎸4鍏/鍚ㄦ敹璐癸紟鈶犻棶鑰佸笀瀹5鏈堜唤鐢ㄦ按18鍚紝闂簲浜ゆ按璐瑰灏戝厓锛熲憽鍚磋佸笀瀹5鏈堜唤浜ゆ按璐65鍏冿紝闂惔鑰佸笀瀹5鏈堜唤鐢ㄦ按澶氬皯鍚紵鑰冪偣锛氫竴鍏冧竴娆℃柟绋嬬殑...
绛旓細140
绛旓細锛1锛夎垂鐢=10脳2+锛16-10锛壝2.5 =20+15 =35鍏 锛2锛夛紙20-10锛壝2.5=25鍏冿紱鐢ㄦ按=锛69-25-10脳2锛壝4+20 =24梅4+20 =26鍚 锛3锛塧鈮10锛涜垂鐢=2a锛10锛渁鈮20锛涜垂鐢=(a-10)脳2.5+10脳2=2.5a-5;a锛20;璐圭敤=(a-20)脳4+10脳2.5+10脳2=4a-80+45=4a-35;鎮ㄥソ锛屽緢...
绛旓細锛1锛10脳2+锛16-10锛壝2.5=35锛堝厓锛夛紝绛旓細搴斾氦姘磋垂35鍏冿紱锛2锛夎榛勮佸笀瀹5鏈堜唤鐢ㄦ按x鍚紝鐢遍鎰忓緱10脳2+2.5脳锛坸-10锛=30锛岃В寰梮=14锛岀瓟锛氶粍鑰佸笀瀹5鏈堜唤鐢ㄦ按14鍚紱锛3锛夆憼褰0锛渁鈮10鏃讹紝搴斾氦姘磋垂涓2a锛堝厓锛夛紝鈶″綋a锛10鏃讹紝搴斾氦姘磋垂涓猴細20+2.5锛坅-10锛=2.5a-5锛堝厓锛...
绛旓細鏌愬競涓榧撳姳鑺傜害鐢ㄦ按锛屽鑷潵姘寸殑鏀惰垂鏍囧噯浣滃涓嬭瀹氾細姣忔湀姣忔埛鐢ㄦ按涓嶈秴杩10鍚ㄧ殑閮ㄥ垎锛屾寜0. 45鍏冿紡鍚ㄦ敹璐癸紱瓒呰繃10鍚ㄨ屼笉瓒呰繃20鍚ㄧ殑閮ㄥ垎锛屾寜0. 80鍏冿紡鍚ㄦ敹璐癸紱瓒呰繃20鍚ㄧ殑閮ㄥ垎鎸1. 50鍏冿紡鍚ㄦ敹璐癸紝鏌愭湀鐢叉埛姣斾箼鎴峰缂存按璐7. 10鍏冿紝涔欐埛姣斾笝鎴峰缂存按璐3. 75鍏冦傞棶鐢层佷箼銆佷笝璇ユ湀鍚勭即姘磋垂澶氬皯...
绛旓細璁炬潕鑰佸笀鍏湀浠鐢ㄦ按x鍚.閭ｄ箞 2.6*10+3*10+锛坸-20锛*3.5=70 鍖栫畝 26+30+3.5x-70=70 鍚堝苟鍚岀被椤瑰緱 3.5x=84 瑙ｅ緱锛歺=24 绛旓細鏉庤佸笀鍏湀浠界敤姘24鍚.
绛旓細鐢ㄦ埛姣忔湀鐢ㄦ按涓嶈秴杩10鍚紝鍒欏簲浜ゆ按璐瑰簲涓嶈秴杩10*1.5=15鍏 鐢ㄦ埛姣忔湀鐢ㄦ按涓嶈秴杩20鍚紝鍒欏簲浜ゆ按璐瑰簲涓嶈秴杩10*1.5+10*2.5=15+25=40鍏 鎵浠ユ潕鑰佸笀瀹跺簲璇ユ槸涓嶈秴杩40鍏 璁鐢ㄦ按閲鏄痻鍚 10*1.5+锛坸-10锛*2.5=30 x=16
绛旓細2a 褰揳<10 2.5a 褰10=<a<20 4a 褰揳>=20
绛旓細(1)鑳¤佸笀鍥涙湀浠鐢ㄦ按18鍚紝搴斾氦姘磋垂锛18*0.75=13.5锛堝厓锛夊嚱鏁板叧绯诲紡:锛2锛墆=0.5x(x<10) y=0.75x(10<x<20)y=1.2x(20<x)(3)鑳¤佸笀浜旀湀浠界敤浜嗗灏戝惃锛氬亣璁捐儭鑰佸笀浜旀湀浠界敤X鍚ㄦ按 X/17=1.2 X=1.2*17 X=20.4鍚 ...
绛旓細3.15+3.75=6.9鍏 4.5<6.9< 12.5 鐢叉埛鐢ㄦ按鍦10鍚ㄤ互涓20鍚ㄤ互涓 6.9-4.5=2.4鍏 2.4/0.8=3鍚 3+10=13鍚 鐢叉埛鐢ㄦ按13鍚 銆2銆4.5<10<12.5 10-4.5=5.5鍏 5.5/0.8=6.875鍚 6.875+10=16.875鍚 鏈澶氱敤姘16.875鍚 銆3銆30>12.5 30...
