Question and Answers Forum

All Questions      Topic List

Relation and Functions Questions

Previous in All Question      Next in All Question      

Previous in Relation and Functions      Next in Relation and Functions      

Question Number 218311 by mr W last updated on 06/Apr/25

Answered by Frix last updated on 06/Apr/25

f(x)=c

$${f}\left({x}\right)={c} \\ $$

Commented by mr W last updated on 06/Apr/25

any proof that this is the only  possibility?

$${any}\:{proof}\:{that}\:{this}\:{is}\:{the}\:{only} \\ $$$${possibility}? \\ $$

Commented by Frix last updated on 06/Apr/25

It seems obvious to me...  Try any function to see what happens:  f(x)=kx+d  kx+d=x+k(kx+d)+d  f(x)=sin x  sin x =sin (x+sin x))  f(x)=x^r   x^r =(x+x^r )^r   f(x)=e^x   e^x =e^(x+e^x )   f(x)=ln x  ln x =ln (x+ln x)  All of these can be solved for x but they  never are true for all x

$$\mathrm{It}\:\mathrm{seems}\:\mathrm{obvious}\:\mathrm{to}\:\mathrm{me}... \\ $$$$\mathrm{Try}\:\mathrm{any}\:\mathrm{function}\:\mathrm{to}\:\mathrm{see}\:\mathrm{what}\:\mathrm{happens}: \\ $$$${f}\left({x}\right)={kx}+{d} \\ $$$${kx}+{d}={x}+{k}\left({kx}+{d}\right)+{d} \\ $$$${f}\left({x}\right)=\mathrm{sin}\:{x} \\ $$$$\left.\mathrm{sin}\:{x}\:=\mathrm{sin}\:\left({x}+\mathrm{sin}\:{x}\right)\right) \\ $$$${f}\left({x}\right)={x}^{{r}} \\ $$$${x}^{{r}} =\left({x}+{x}^{{r}} \right)^{{r}} \\ $$$${f}\left({x}\right)=\mathrm{e}^{{x}} \\ $$$$\mathrm{e}^{{x}} =\mathrm{e}^{{x}+\mathrm{e}^{{x}} } \\ $$$${f}\left({x}\right)=\mathrm{ln}\:{x} \\ $$$$\mathrm{ln}\:{x}\:=\mathrm{ln}\:\left({x}+\mathrm{ln}\:{x}\right) \\ $$$$\mathrm{All}\:\mathrm{of}\:\mathrm{these}\:\mathrm{can}\:\mathrm{be}\:\mathrm{solved}\:\mathrm{for}\:{x}\:\mathrm{but}\:\mathrm{they} \\ $$$$\mathrm{never}\:\mathrm{are}\:\mathrm{true}\:\mathrm{for}\:\mathrm{all}\:{x} \\ $$

Terms of Service

Privacy Policy

Contact: info@tinkutara.com