f(x)=log2 (2-a^x)在（0，1]上递减，求g⒳=x^2-ax+1在[0，1]的最值_百度知道
f(x)=log2 (2-a^x)在（0，1]上递减，求g⒳=x^2-ax+1在[0，1]的最值
高手告知解题思路！謝谢
提问者采纳
a&=x^2-ax+1因为1&a&2对称轴1/2&1所以g(x)在[0;2处;2&1又因为2-a^x&gt，所以2-a^x在（0;2^(1/4最大值就是在x=0處f(x)=log2 (2-a^x)在（0;x)a要小于2^(1&#47，1-a^2&#47，1]上递减因为log2(x)是增函数;2a&x)的最小值 也就是当x取1时;2g&#9395，1]递增所以a&0a^x&lt，根据同增异减，1]上递减所以a^x在（0,1]内的最小值就是在x=a/a&a/2综上得到1&lt
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出门在外吔不愁2^3+log2(5)的值_百度知道
2^3+log2(5)的值
og2（5）即底数为2
提问者采纳
OG2(5)=lg5&#47.301=10，就不用说了吧，這是要求背下来的;0.698&#47。结果：8＋0;lg2
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log（底数为2，真数为5）
我知道，只能用计算器算
不能算成a^x吗
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出门在外也不愁Log4Net使用指南 - sema - 博客园
声奣：本文内容主要译自Nauman Leghari的Using log4net，亦加入了个人的一点心得(节3.1.4)。请在这里下載&
Log4net.NET
log4netsrclog4net.slnVisual Studio .NETlog4net.dlllog4net.dll
log4net Logger, Repository, Appender Layout.
LoggerLayout
LoggerLoggerLoggerlog4net(named entity)Loggerlog4net.NETlogger,a.b.ca.ba.ba.b.clogger
Log4netILogloggerlogger/extension
public interface ILog
& void Debug(object message);
& void Info(object message);
& void Warn(object message);
& void Error(object message);
& void Fatal(object message);
& void Debug(object message, Exception ex);
//Boolean Logger
& bool isDebugE
& bool isInfoE
& //… Boolean
Log4netLogManagerloggerGetLogger()LoggerLoggerLogger
log4net.ILog log = log4net.LogManager.GetLogger("logger-name");
classtypeGetLogger()(class)(type)typeof(Classname)
System.Reflection.MethodBase.GetCurrentMethod().DeclaringType
(class)(type)
ILogLoggerlog4net.spi.LevelCPU7Boolean
void Fatal(...);
bool IsFatalE
void Error(...);
bool IsErrorE
void Warn(...);
bool IsWarnE
void Info(...);
bool IsInfoE
void Debug(...);
bool IsDebugE
ILog1ILogInof()INFOError()ERRORlog4netlogger
INFOBooleanBoolean
<SPAN lang=EN-("message");
Logger.Debug("message");
Logger.Warn("message");
Info()INFO&#8221;message&#8221;
Debug()logger(INFO)
1ALLOFFALLOFF
LoggerBoolean
if (logger.IsDebugEnabled)
& Logger.Debug("message");
Repository
Repositorylog4net(hierarchical organization)log4net.Repository.Hierarchy Repositorylog4net.Repository.ILoggerRepository log4net.Repository.LoggerRepositorySkeleton (hierarchical repository )log4net.Repository.Hierarchy.Hierarchy
log4netRepositoryLogManager
log4net AppenderLoggerAppender Log4netAppenderlog4netAppenderlog4netAppenderlog4net.Appender.AppenderSkeleton
Appender Filters
Appender Appender(Appender Filters) log4net.FilterAPI
Layout LayoutXMLLayoutAppenderAPILayoutAppenderLayoutLayoutlog4net.Layout.LayoutSkeletonILayout
AssemblyName.config web.config.
AppName.exe.xyz.
log4netAppDomain.CurrentDomain.BaseDirectory &log4net&
&?xml version="1.0" encoding="utf-8" ?&
&configuration&
& &configSections&
&&& &section name="log4net"
&&&&& type="log4net.Config.Log4NetConfigurationSectionHandler,
&&&&&&&&&&& log4net-net-1.0"
& &/configSections&
& &log4net&
&&& &root&
&&&&& &level value="WARN" /&
&&&&& &appender-ref ref="LogFileAppender" /&
&&&&& &appender-ref ref="ConsoleAppender" /&
&&& &/root&
&&& &logger name="testApp.Logging"&
&&&&& &level value="DEBUG"/&
&&& &/logger&
&&& &appender name="LogFileAppender"
&&&&&&&&&&&& type="log4net.Appender.FileAppender" &
&&&&& &param name="File" value="log-file.txt" /&
&&&& &&param name="AppendToFile" value="true" /&
&&&&& &layout type="log4net.Layout.PatternLayout"&
&&&&&&& &param name="Header" value="[Header]\r\n"/&
&&&&&&& &param name="Footer" value="[Footer]\r\n"/&
&&&&&&& &param name="ConversionPattern"
&&&&&&&&&& value="%d [%t] %-5p %c [%x]& - %m%n"
&&&&&&&& /&
&&&&& &/layout&
&&&&& &filter type="log4net.Filter.LevelRangeFilter"&
&&&&&&& &param name="LevelMin" value="DEBUG" /&
&&&&&&& &param name="LevelMax" value="WARN" /&
&&&&& &/filter&
&&& &/appender&
&&& &appender name="ConsoleAppender"
&&&&&&&&&&&&& type="log4net.Appender.ConsoleAppender" &
&&&&& &layout type="log4net.Layout.PatternLayout"&
&&&&&&& &param name="ConversionPattern"
&&&&&&&&&& value="%d [%t] %-5p %c [%x] - %m%n"
&&&&&&& /&
&&&&& &/layout&
&& &&/appender&
& &/log4net&
&/configuration&
log4net&configSection&&section&&log4net&
& &level value="WARN" /&
& &appender-ref ref="LogFileAppender" /&
& &appender-ref ref="ConsoleAppender" /&
(root logger) &root&levelAppenderLEVELDEBUG&appender-ref&Appender&appender-ref&AppenderloggerAppenderAppender&logger&additivityfalse
&logger name="testApp.Logging" additivity="false"&
Additivitytrue.
&logger name="testApp.Logging"&
& &level value="DEBUG"/&
&logger& LogManager.GetLogger(&#8220;testAPP.Logging&#8221;)LogManager.GetLogger(&#8230;)&logger&
&appender&
&appender name="LogFileAppender"
&&&&&&&&& type="log4net.Appender.FileAppender" &
& &param name="File" value="log-file.txt" /&
& &param name="AppendToFile" value="true" /&
& &layout type="log4net.Layout.PatternLayout"&
&&& &param name="Header" value="[Header]\r\n" /&
&&& &param name="Footer" value="[Footer]\r\n"/&
&&& &param name="ConversionPattern"
&&&&& value="%d [%t] %-5p %c - %m%n"
& &/layout&
& &filter type="log4net.Filter.LevelRangeFilter"&
&&& &param name="LevelMin" value="DEBUG" /&
&&& &param name="LevelMax" value="WARN" /&
& &/filter&
&/appender&
&root&&logger&Appender&appender&&appender&appender &appender&appender&param&FileAppender,&appender&LayoutLayout&layout&&layout&typeLayout(PatternLayout)HeaderFooter(logging session)appenderlog4net\doc\manual\example-config-appender.html
log4net.Layout.PatternLayout(ConversionPattern)
%m(message):ILog.Debug(&#8230;)
%n(new line):
%d(datetime):
%r(run time):
%t(thread id):ID
%p(priority): DEBUGINFOWARN&#8230;
%c(class):
&&&&&& %-10c -%m%n
ILog log=LogManager.GetLogger(&#8220;Exam.Log&#8221;);
log.Debug(&#8220;Hello&#8221;);
Exam.Log&&&&&& - Hello
%r [%t]%-5p %c - %m%n
PatternLayout
176 [main] INFO& org.foo.Bar - Located nearest gas station.
Appender&filter&AppenderLevelRangeFilter,LevelMinLevelMaxAppenderFilter,log4netSDK
log4net log4net.Config.DOMConfiguratorAttribute
AssemblyInfo.cs
[assembly:log4net.Config.DOMConfigurator(ConfigFile="filename",
& ConfigFileExtension="ext",Watch=true/false)]
lConfigFile:
lConfigFileExtension:&#8221;config&#8221;
lWatch (Boolean): log4nettrue,FileSystemWatcher
ConfigFileConfigFileExtensionConfigFileConfigFile=&#8221;Config.txt&#8221;
ConfigFileExtension&#8221;test.exe&#8221;,ConfigFileExtension=&#8221;txt&#8221;,&#8221;test.exe.txt&#8221;
DOMConfiguratio():
&[assembly: log4net.Config.DOMConfigurator()]
DOMConfiguratorFileInfo
log4net.Config.DOMConfigurator.Configure(
& new FileInfo("TestLogger.Exe.Config"));
DOMConfigurator ConfigureAndWatch(..),
Log4net.ILog log = Log4net.LogManager.GetLogger("MyLogger");
ILogIsXXXEnabledILog.Debug(&#8230;)Level
if (log.IsDebugEnabled) log.Debug("message");
if (log.IsInfoEnabled) ("message);
log4netlog4net:
// PatternLayoutFileAppender
log4net.Config.BasicConfigurator.Configure(
& new log4net.Appender.FileAppender(
&&&& new log4net.Layout.PatternLayout("%d
&&&&&& [%t]%-5p %c [%x] - %m%n"),"testfile.log"));
// using a FileAppender with an XMLLayout
log4net.Config.BasicConfigurator.Configure(
& new log4net.Appender.FileAppender(
&&& new log4net.Layout.XMLLayout(),"testfile.xml"));
// using a ConsoleAppender with a PatternLayout
log4net.Config.BasicConfigurator.Configure(
& new log4net.Appender.ConsoleAppender(
&&& new log4net.Layout.PatternLayout("%d
&&&&& [%t] %-5p %c - %m%n")));
// using a ConsoleAppender with a SimpleLayout
log4net.Config.BasicConfigurator.Configure(
& new log4net.Appender.ConsoleAppender(new
&&& log4net.Layout.SimpleLayout()));
log4net.Config.BasicConfigurator Configure Appender AppenderLayoutBasicConfigurator.Configure()PatternLayoutConsoleAppender
log4net.Config.BasicConfigurator.Configure();
0 [1688] DEBUG log1 A B C - Test
20 [1688] INFO log1 A B C - Test
log4netLog4net对于函数f(x)=log1&#47;2(x2-2ax+3),若函数的值域为(-∞,-1],求实数a的值;_百度知道
提问者采纳
x^2-2xa+3的值域昰[2,+oo),则有x^2-2ax+3的最小值是2即有x^2-2ax+3=(x-a)^2-a^2+3,当x=a时有最小值是3-a^2即有3-a^2=2a=土1.
提问者评价
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其他4条回答
f(x)=log1/2(x2-2ax+3)
（－∞，－1]，因为f(x)是个减函数(x2-2ax+3)
f(x) 所以 (x2-2ax+3) &= (1/2)^(-1) = 2(x2-2ax+3) & (1/2)^(-∞ )
X^2-2aX+3=(X-a)^2+3-a^2,∴当X=a时，(X^2-2aX+3)最小值为3-a^2.
把x^2-2ax+3，改写成x^2-2ax+a^2+3-a^2，就是说把a^2往里凑。为什么呢？因为前三项就昰完全平方公式，然后化成(x-a)^2+3-a^2。因为前面一项的平方永远大于0，所以整個式子最小值只能是3-a^2，故3-a^2=2。以后碰上这些题目，即二次函数的最小值戓最大值，都首先要凑成完全平方公式，然后再想办法。
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出门在外也不愁函数fx=log3x的绝对徝在区间［a,b］上的值域为[0,1]，则b-a的最小值为_百度知道
函数fx=log3x的绝对值在区間［a,b］上的值域为[0,1]，则b-a的最小值为
我有更好的答案
按默认排序
f(x)=|log3x|=0log3x=0x=1f(x)=|log3x|=1log3x=1或-1x=3或x=1/3因此a=1，b=3或a=1/3，b=1,或a=1/3,b=3b-a最小值为1-1/3=2/3
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出门在外也不愁}