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Question Number 3017 by Filup last updated on 03/Dec/15
A=∫_μ ^( μ+ε)  (dx/(x+n))    A=ln(x+n) ∣_μ ^(μ+ε)   =ln(μ+ε+n)−ln(μ+n)  =ln(((μ+ε+n)/(μ+n)))  =ln(((μ+n)/(μ+n))+(ε/(μ+n)))    ∴A=∫_μ ^( μ+ε)  (dx/(x+n))=ln((ε/(μ+n))+1)    For  (a/b)=c  i) if  a>b, c>1  ii) if   a<b, c<1  iii) if  a=b, c=1    Case (i)  ε>μ+n  (ε/(μ+n))>1  ∴A>ln(2)    Case (ii)  ε<μ+n  (ε/(μ+n))<1  ∴A<ln(2)    Case (iii)  ε=μ+n  (ε/(μ+n))=1  A=ln(2)    What other observations can you find  regarding similar logarithmic functions?
$${A}=\int_{\mu} ^{\:\mu+\epsilon} \:\frac{{dx}}{{x}+{n}} \\ $$$$ \\ $$$${A}=\mathrm{ln}\left({x}+{n}\right)\:\mid_{\mu} ^{\mu+\epsilon} \\ $$$$=\mathrm{ln}\left(\mu+\epsilon+{n}\right)−\mathrm{ln}\left(\mu+{n}\right) \\ $$$$=\mathrm{ln}\left(\frac{\mu+\epsilon+{n}}{\mu+{n}}\right) \\ $$$$=\mathrm{ln}\left(\frac{\mu+{n}}{\mu+{n}}+\frac{\epsilon}{\mu+{n}}\right) \\ $$$$ \\ $$$$\therefore{A}=\int_{\mu} ^{\:\mu+\epsilon} \:\frac{{dx}}{{x}+{n}}=\mathrm{ln}\left(\frac{\epsilon}{\mu+{n}}+\mathrm{1}\right) \\ $$$$ \\ $$$$\mathrm{For}\:\:\frac{{a}}{{b}}={c} \\ $$$$\left.{i}\right)\:\mathrm{if}\:\:{a}>{b},\:{c}>\mathrm{1} \\ $$$$\left.{ii}\right)\:\mathrm{if}\:\:\:{a}<{b},\:{c}<\mathrm{1} \\ $$$$\left.{iii}\right)\:\mathrm{if}\:\:{a}={b},\:{c}=\mathrm{1} \\ $$$$ \\ $$$$\mathrm{Case}\:\left({i}\right) \\ $$$$\epsilon>\mu+{n} \\ $$$$\frac{\epsilon}{\mu+{n}}>\mathrm{1} \\ $$$$\therefore{A}>\mathrm{ln}\left(\mathrm{2}\right) \\ $$$$ \\ $$$$\mathrm{Case}\:\left({ii}\right) \\ $$$$\epsilon<\mu+{n} \\ $$$$\frac{\epsilon}{\mu+{n}}<\mathrm{1} \\ $$$$\therefore{A}<\mathrm{ln}\left(\mathrm{2}\right) \\ $$$$ \\ $$$$\mathrm{Case}\:\left({iii}\right) \\ $$$$\epsilon=\mu+{n} \\ $$$$\frac{\epsilon}{\mu+{n}}=\mathrm{1} \\ $$$${A}=\mathrm{ln}\left(\mathrm{2}\right) \\ $$$$ \\ $$$$\mathrm{What}\:\mathrm{other}\:\mathrm{observations}\:\mathrm{can}\:\mathrm{you}\:\mathrm{find} \\ $$$$\mathrm{regarding}\:\mathrm{similar}\:\mathrm{logarithmic}\:\mathrm{functions}? \\ $$
Commented by Filup last updated on 03/Dec/15
Maybe look at cases of ∫_μ ^( με) , ∫_μ ^( μ^ε ) , etc.
$$\mathrm{Maybe}\:\mathrm{look}\:\mathrm{at}\:\mathrm{cases}\:\mathrm{of}\:\int_{\mu} ^{\:\mu\epsilon} ,\:\int_{\mu} ^{\:\mu^{\epsilon} } ,\:{etc}. \\ $$
Commented by 123456 last updated on 03/Dec/15
μ>−n∨μ+ε<−n
$$\mu>−{n}\vee\mu+\epsilon<−{n} \\ $$
Commented by Filup last updated on 03/Dec/15
Please elaborate?
$$\mathrm{Please}\:\mathrm{elaborate}? \\ $$
Answered by Filup last updated on 03/Dec/15
∫_μ ^(με)  (dx/(x+n))=ln(((με+n)/(μ+n)))  =ln(((ε+(n/μ))/(1+(n/μ))))    k=(n/μ)  A=ln(((ε+k)/(1+k)))    Similar to original post:  ε>1, A>0  ε<1, A<0  ε=1, A=0
$$\int_{\mu} ^{\mu\epsilon} \:\frac{{dx}}{{x}+{n}}=\mathrm{ln}\left(\frac{\mu\epsilon+{n}}{\mu+{n}}\right) \\ $$$$=\mathrm{ln}\left(\frac{\epsilon+\frac{{n}}{\mu}}{\mathrm{1}+\frac{{n}}{\mu}}\right) \\ $$$$ \\ $$$${k}=\frac{{n}}{\mu} \\ $$$${A}=\mathrm{ln}\left(\frac{\epsilon+{k}}{\mathrm{1}+{k}}\right) \\ $$$$ \\ $$$$\mathrm{Similar}\:\mathrm{to}\:\mathrm{original}\:\mathrm{post}: \\ $$$$\epsilon>\mathrm{1},\:{A}>\mathrm{0} \\ $$$$\epsilon<\mathrm{1},\:{A}<\mathrm{0} \\ $$$$\epsilon=\mathrm{1},\:{A}=\mathrm{0} \\ $$$$ \\ $$

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