日韩亚洲一区中文字幕,日韩欧美三级中文字幕在线,国产伦精品一区二区三区,免费在线欧美性爱链接

      1. <sub id="o5kww"></sub>
        
<legend id="o5kww"></legend>
        <style id="o5kww"><abbr id="o5kww"></abbr></style>
        <strong id="o5kww"><u id="o5kww"></u></strong>
        

        2. 


          
	
          
		
	
          
	
          
		
          
			
		
          
		
          
	
          

          



          

          

          


          

          
	
          
				
          

			
				 解:(1)設(shè)藥物燃燒階段函數(shù)解析式為.由題意得:  ························································································································ 2分  ．此階段函數(shù)解析式為······································································· 3分  (2)設(shè)藥物燃燒結(jié)束后的函數(shù)解析式為.由題意得:  ·························································································································· 5分  ．此階段函數(shù)解析式為······································································ 6分  (3)當(dāng)時(shí).得···················································································· 7分  ························································································································· 8分    ·························································································································· 9分  從消毒開始經(jīng)過50分鐘后學(xué)生才可回教室．···························································· 10分			【查看更多】
			


		
           
          


		
          
		
          題目列表(包括答案和解析)
          

		
		
          

          


          
	
          				
          
									
          方程
          x+2
          x
          +
          x
          3x+6
          =2，用換元法解，若設(shè)
          x+2
          x
          =y，則此方程化為整式方程的是（　�。�
          

			
          
				查看答案和解析>>
			
          
		
          
				
          
									
          七年級(jí)學(xué)生參加了社會(huì)實(shí)踐調(diào)查活動(dòng)，到生態(tài)果園調(diào)查后得到如下信息：今年收獲了15噸李子和8噸桃子，要租用甲、乙兩種貨車共6輛，及時(shí)運(yùn)往外地，經(jīng)詢問，甲種貨車可裝李子4噸和桃子1噸，乙種貨車可裝李子1噸和桃子3噸．根據(jù)同學(xué)們帶回的信息，試探究以下問題：
          （1）共有幾種租車方案？
          （2）經(jīng)咨詢運(yùn)輸公司，甲種貨車每輛需付運(yùn)費(fèi)1000元，乙種貨車每輛需付運(yùn)費(fèi)700元，試幫助選出最佳方案，并求出此方案運(yùn)費(fèi)是多少．
          請(qǐng)同學(xué)們補(bǔ)充完成下列部分解題過程：
          （1）解：
          ①若設(shè)租用甲車x輛，則租用乙車
          （6-x）
          （6-x）
          輛，
          ②由題意可知：甲車一共可裝
          x
          x
          噸桃子，乙車一共可裝
          3（6-x）
          3（6-x）
          噸桃子，則甲，乙兩種車一共可裝
          x+3（6-x）
          x+3（6-x）
          噸桃子．（用含有x的代數(shù)式表示）
          請(qǐng)列出不等式
          x+3（6-x）≥8
          x+3（6-x）≥8

          ③甲車一共可裝
          4x
          4x
          噸李子，乙車一共可裝
          （6-x）
          （6-x）
          噸李子，則甲，乙兩種車一共可裝
          4x+（6-x）
          4x+（6-x）
          噸李子．（用含有x的代數(shù)式表示）
          請(qǐng)列出不等式
          4x+（6-x）≥15
          4x+（6-x）≥15

          ④請(qǐng)列出不等式組，并求出滿足不等組的整數(shù)解，寫出相應(yīng)的方案
          （2）解：
          

			
          
				查看答案和解析>>
			
          
		
          
				
          
									
          25、已知：兩個(gè)正整數(shù)的和與積相等，求這兩個(gè)正整數(shù)．
          解：不妨設(shè)這兩個(gè)正整數(shù)為a、b，且a≤b．
          由題意，得ab=a+b，（*）
          則ab=a+b≤b+b=2b，所以a≤2，
          因?yàn)閍為正整數(shù)，所以a=1或2，
          ①當(dāng)a=1時(shí)，代入等式（*），得1•b=1+b，b不存在；
          ②當(dāng)a=2時(shí)，代入等式（*），得2•b=2+b，b=2．
          所以這兩個(gè)正整數(shù)為2和2．
          仔細(xì)閱讀以上材料，根據(jù)閱讀材料的啟示，思考是否存在三個(gè)正整數(shù)，它們的和與積相等試說明你的理由．
          

			
          
				查看答案和解析>>
			
          
		
          
				
          
									
          用換元法解方程,若設(shè),則原方程化為關(guān)于的整式方程是
          


          A、         
  B、        
          


          C、               
D、
          


           
          

			
          
				查看答案和解析>>
			
          
		
          
				
          
									
          用換元法解方程，設(shè)，那么原方程可化為    ．
          

			
          
				查看答案和解析>>
			
          
		
          
						
          
				
          
	
          
	
          
		
          


          同步練習(xí)冊(cè)答案