由 aa2191943 於 星期一 七月 24, 2006 10:33 pm
#ed_op#DIV#ed_cl##ed_op#DIV#ed_cl#第一題不知是何處的考題, 現在這題幾乎是每本講義必備的對數題目; #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#(不過我現在是自己想, 沒去翻講義, 也不確定正不正確)#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#log x = a + log A#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#log (10/x)= b + log B#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#其中a,b為整數, A,B=[1,10)#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#→ 1 = (a+b) + log(AB)#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#→ a+b = 0或1#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#討論:#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#1. a+b = 0, a#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#- 2b#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#= -a#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#< 0#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#2. a+b = 1, a#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#- 2b#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#= (1-b)#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl# -2b#ed_op#SUP#ed_cl#2 #ed_op#/SUP#ed_cl#= -b#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl#-2b+1= -(b+1)#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl#+2#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#a=2, b=-1, max=2 (此時 x=100)#ed_op#/DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl#