某市为了鼓励居民节约用水，对自来水用户按如下标准收费：若每月每户用水不超过10吨
\u67d0\u5e02\u4e3a\u4e86\u9f13\u52b1\u5c45\u6c11\u8282\u7ea6\u7528\u6c34\uff0c\u5bf9\u81ea\u6765\u6c34\u7528\u6237\u6309\u5982\u4e0b\u6807\u51c6\u6536\u8d39\uff1b\u82e5\u6bcf\u6708\u6bcf\u6237\u7528\u6c34\u4e0d\u8d85\u8fc712\u7acb\u65b9\u7c73\uff0c\u6309\u6bcf\u7acb\u65b9\u7c73a \u5143\u6839\u636e\u82e5\u6bcf\u6708\u6bcf\u6237\u7528\u6c34\u4e0d\u8d85\u8fc712\u7acb\u65b9\u7c73\uff0c\u6309\u6bcf\u7acb\u65b9\u7c73a \u5143\u6536\u8d39\uff1b\u82e5\u8d85\u8fc712\u7acb\u65b9\u7c73\uff0c\u5219\u8d85\u8fc7\u90e8\u5206\u6bcf\u7acb\u65b9\u7c73\u63092a\u5143\u6536\u8d39\uff0c\u2234\u5c45\u6c11\u4e94\u6708\u4efd\u4ea4\u6c34\u8d39y\uff08\u5143\uff09\u4e0e\u7528\u6c34\u91cfx\uff08\u7acb\u65b9\u7c73\uff09\uff08x\uff1e12\uff09\u4e4b\u95f4\u7684\u5173\u7cfb\u5f0f\u4e3a\uff1ay=12a+\uff08x-12\uff09?2a=2ax-12a\uff0c\uff08x\uff1e12\uff09\uff1b\u8bbe\u8fd9\u4e2a\u6708\u5b9e\u9645\u7528\u6c34x\u5428\uff0c\u6839\u636e\u9898\u610f\u5f97\uff1a12a+\uff08x-12\uff09?2a=20a\uff0c\u89e3\u5f97\uff1ax=16\uff0e\u6545\u7b54\u6848\u4e3a\uff1ay=2ax-12a\uff08x\uff1e12\uff09\uff0c16\uff0e
\u7531\u9898\u610f\u5f97\uff1a15a+\uff0835-15\uff09?2a=15a+40a=55a\uff0c\u6545\u7b54\u6848\u4e3a\uff1a55a\uff0e
由题意得， 0.45×10＝4.5元0.8×10＝8元
8＋4.5＝12.5元
∵12.5元＜14元
∴李老师家的用水量为 10+10+（14-12.5）÷1.5
＝20+1
＝21（元）
绛旓細璁鐢ㄦ按X鍚.0.45*10+锛圶-20锛*1.5+0.8*10=14 杩欓亾绠楀紡0.45*10 灏辨槸鍛婅瘔浣10鍚ㄧ殑姘翠环 0.8*10灏辨槸鍛婅瘔浣20鍚ㄤ腑瓒呭嚭10鍚ㄧ殑閭10鍚ㄤ环鏍 鑰1.5锛圶-20锛夋槸鍛婅瘔浣犺秴鍑20鍚ㄤ互鍚庣殑浠锋牸.鑰岃繖3涓姞璧锋潵灏涓鎬讳环鏍间簡 4.5+1.5X-30+8=14 1.5X-17.5=14 1.5X=31.5 X=21 ...
绛旓細鏍规嵁鑻ユ瘡鏈堟瘡鎴风敤姘翠笉瓒呰繃12绔嬫柟绫筹紝鎸夋瘡绔嬫柟绫砤 鍏冩敹璐癸紱鑻ヨ秴杩12绔嬫柟绫筹紝鍒欒秴杩囬儴鍒嗘瘡绔嬫柟绫虫寜2a鍏冩敹璐癸紝鈭灞呮皯浜旀湀浠戒氦姘磋垂y锛堝厓锛変笌鐢ㄦ按閲x锛堢珛鏂圭背锛夛紙x锛12锛変箣闂寸殑鍏崇郴寮涓锛歽=12a+锛坸-12锛?2a=2ax-12a锛岋紙x锛12锛夛紱璁捐繖涓湀瀹為檯鐢ㄦ按x鍚紝鏍规嵁棰樻剰寰楋細12a+锛坸-12锛?2a=20a锛岃В寰楋細...
绛旓細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鐢ㄦ按24鍚.
绛旓細10鍚ㄥ埌20鍚ㄩ儴鍒嗘寜4.00鍏/鍚紝鍦ㄨ繖涓闃舵璐圭敤鏈澶涓锛2.4*10+4.0*10=64鍏 瓒呰繃20鍚ㄩ儴鍒嗘寜6.50鍏/鍚ㄦ敹璐癸細鏁呰垂鐢ㄩ珮浜64鍏冨氨涓瀹氳秴鍑20鍚姘达紝鎶20鍚ㄧ殑璐圭敤锛64鍏冿級鎵ｉ櫎鍚庣殑閮ㄥ垎鐢6.50鍏/鍚ㄦ潵绠楃湅瓒呭嚭鐨勬暟閲忥細锛70.50-64)/6.5=1鍚 鏁呮诲叡鐢ㄦ按閲锛20+1=21鍚 ...
绛旓細瑙ｏ細鍋囪灞呮皯姣忔湀鐢12鍚ㄦ按鍒欐按璐逛负12A 浣嗗疄闄呮按璐逛负20A 鎵浠20A-12A=8A鐨勮秴鍑12鍚ㄦ按璐 瓒呭嚭12鍚ㄦ按姘磋垂鎸2A鍏冩瘡鍚ㄦ敹鍙 鎵浠ヨ秴鍑烘按涓8A/2A=4鍚ㄦ按 鎵浠 瀹為檯鐢ㄦ按涓12+4=16鍚ㄦ按
绛旓細锛1锛20脳2.3锛10脳3.45锛2脳4.6锛23锛34.5锛9.2锛66.7锛堝厓锛夛紙2锛59.8-20脳2.3-10脳3.45=2.3锛堝厓锛2.3梅4.6=0.5锛堢珛鏂圭背锛30锛0.5=30.5锛堢珛鏂圭背锛
绛旓細16
绛旓細瑙ｏ細璁惧垯璇灞呮皯杩欎釜鏈堝疄闄鐢ㄦ按x鍚 鍒12a+(x-12)2a=20a x=16 绛旓細 璇ュ眳姘戣繖涓湀瀹為檯鐢ㄦ按16鍚
绛旓細甯冨徑灏忓瓙锛屼綘濂斤細鏍囧噯鍐咃細12脳a锛12a 鏍囧噯澶栵細锛20a-12a锛壝2a锛4锛堝惃锛夎灞呮皯杩欎釜鏈鐢ㄦ按锛12锛4锛16锛堝惃锛=== 瑙ｏ細璁捐繖涓湀鐢ㄦ按X鍚 12a锛嬶紙X锛12锛壝2a锛20a 12a锛2aX锛24a锛20a 2aX锛32a X锛16
绛旓細瑙ｏ細璁鐢ㄦ按 x 鍚 12 * 1.8 = 21.6鍏 < 50.4鍏 鈭 璇ョ敤鎴风敤姘磋秴杩12鍚 鏈 21.6 + 3.6 * 锛坸 - 12锛 = 50.4 寰 x = 20 绛旓細鐢ㄦ按20鍚
