# logarithmic functions

by Erin_Sharpe
Tags: functions, logarithmic
 P: 17 y = logx 4 identify the domain and range state whether the function is increasing or decreasing, and identify the vertical asympotote, teh x-intercept and the value of x at y = 1 I need some help! thank you in advance!
 Sci Advisor P: 5,935 The 4 in your expression appears to be hanging out in space. It would be helpful if you could write the equation more clearly.
 Sci Advisor HW Helper P: 11,863 So your function is: $$y(x)=\log_{x} 4$$ Can you determine the domain and range...?? Discuss the sign of its derivative... Daniel. P.S.Can u solve the equation y(x*)=1??Find x*...
Math
Emeritus
Thanks
PF Gold
P: 38,877

## logarithmic functions

I believe that loga(x) is only defined for a> 0. Does that help.
 Sci Advisor HW Helper P: 1,123 Also I don't think that loga(x) is defined for a=1.
 Sci Advisor HW Helper P: 11,863 Write $$y(x)=\frac{\ln 4}{\ln x}$$ Cau u see now what is the range??What about the domain? Daniel.
 P: 17 See I thought x was 2??
 Sci Advisor HW Helper P: 11,863 What "2"??Where did u pick it out???You mean the solution to the equation $$\frac{\ln 4}{\ln x} =1$$ I hope you're only kidding... Daniel.
 P: 17 no, i'm kidding. this problem might as well be in chinese for all i understand of it
 P: 17 *** NOT kidding
 Sci Advisor HW Helper P: 11,863 Write it like that $$\ln 4=\ln x$$ Use the fact that logaritm is a surjective function... Daniel.
 P: 17 i'm sorry i'm not trying to be difficult i just completely dont understand what you are talking about.