如题所述
解ï¼ï¼1ï¼ f(x)=m·eçx次æ¹-lnx
fï¼(x)=m·eçx次æ¹-1/x
âµ å ¶æå¼ç¹å°±æ¯å¯¼æ°ä¸ºé¶çç¹
â´ fï¼(x)=m·eçx次æ¹-1/x=0
fï¼(1)=m·e -1 =0
â´ m=1/e
â´ f(x)=1/e·eçx次æ¹-lnx=·eçx-1次æ¹-lnx
f(x)= eçx-1次æ¹-lnx
â´ å½xï¼1 fï¼(x)ï¼0 å½æ°ä¸ºå¢å½æ°ã
å½0ï¼xï¼1 fï¼(x)ï¼0 å½æ°ä¸ºåå½æ°ã
å½ xï¼0 fï¼(x)ï¼0 å½æ°ä¸ºåå½æ°ã
å ¶ä¸0为é´æç¹ã
ï¼2ï¼ f(x)=m·eçx次æ¹-lnx
å½ mâ¥1/e2 æ¶ âµ f(x)=m·eçx次æ¹-lnx
â´ m·eçx次æ¹-lnx â¥1/e2 ·eçx次æ¹-lnx
â´ f(x)â¥1/e2 ·eçx次æ¹-lnx =eçx-2次æ¹-lnx
f(x)â¥eçx-2次æ¹-lnx
ä»å¾å ç f(x)=eçx-2次æ¹
f(x)=lnx
以ä¸ä¸¤ä¸ªå¾åæ°¸è¿ä¸ç¸äº¤ï¼å¹¶ä¸f(x)=eçx-2次æ¹æ°¸è¿å¨ f(x)=lnxçä¸æ¹ã
â´ eçx-2次æ¹-lnx ï¼0 â´ f(x)ï¼0
fï¼(x)=m·eçx次æ¹-1/x
âµ å ¶æå¼ç¹å°±æ¯å¯¼æ°ä¸ºé¶çç¹
â´ fï¼(x)=m·eçx次æ¹-1/x=0
fï¼(1)=m·e -1 =0
â´ m=1/e
â´ f(x)=1/e·eçx次æ¹-lnx=·eçx-1次æ¹-lnx
f(x)= eçx-1次æ¹-lnx
â´ å½xï¼1 fï¼(x)ï¼0 å½æ°ä¸ºå¢å½æ°ã
å½0ï¼xï¼1 fï¼(x)ï¼0 å½æ°ä¸ºåå½æ°ã
å½ xï¼0 fï¼(x)ï¼0 å½æ°ä¸ºåå½æ°ã
å ¶ä¸0为é´æç¹ã
ï¼2ï¼ f(x)=m·eçx次æ¹-lnx
å½ mâ¥1/e2 æ¶ âµ f(x)=m·eçx次æ¹-lnx
â´ m·eçx次æ¹-lnx â¥1/e2 ·eçx次æ¹-lnx
â´ f(x)â¥1/e2 ·eçx次æ¹-lnx =eçx-2次æ¹-lnx
f(x)â¥eçx-2次æ¹-lnx
ä»å¾å ç f(x)=eçx-2次æ¹
f(x)=lnx
以ä¸ä¸¤ä¸ªå¾åæ°¸è¿ä¸ç¸äº¤ï¼å¹¶ä¸f(x)=eçx-2次æ¹æ°¸è¿å¨ f(x)=lnxçä¸æ¹ã
â´ eçx-2次æ¹-lnx ï¼0 â´ f(x)ï¼0
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