若10的2y次=25,求y 請附上解法,謝謝!國中 回應 Lizhong Re: who can help me? 2004-09-27 00:50 10^2y=25 等號兩邊取"對數" log10^2y=log25 2y=2log5 y=log5 (可參考：高中數學第二冊，指數與對數) (查表可得log5約等於0.699)
Lizhong Re: who can help me? 2004-09-27 00:50 10^2y=25 等號兩邊取"對數" log10^2y=log25 2y=2log5 y=log5 (可參考：高中數學第二冊，指數與對數) (查表可得log5約等於0.699)
回應
Lizhong
Re: who can help me?
2004-09-27 00:50等號兩邊取"對數"
log10^2y=log25
2y=2log5
y=log5
(可參考：高中數學第二冊，指數與對數)
(查表可得log5約等於0.699)