How to determine $f(0)$?











up vote
-1
down vote

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$$f(ax+b) = x$$
$$f(a) = dfrac{b}{a}$$



I want to determine $f(0)$ from given equations.



My attempt:



$$f(a)= dfrac{b}{a} implies f(0) = dfrac{b}{0} = text{undefined} $$



However, directly determining $f(0)$ makes no sense in this case. Could you assist me with that?










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  • 1




    Substitute $x=dfrac{-b}{a}$.
    – Yadati Kiran
    Nov 25 at 17:14












  • Surely $a$ is a constant here and not a variable?
    – Mark Bennet
    Nov 25 at 17:16










  • @Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
    – Rebellos
    Nov 25 at 17:19












  • @Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
    – Enzo
    Nov 25 at 17:19












  • @Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
    – Rebellos
    Nov 25 at 17:22















up vote
-1
down vote

favorite












$$f(ax+b) = x$$
$$f(a) = dfrac{b}{a}$$



I want to determine $f(0)$ from given equations.



My attempt:



$$f(a)= dfrac{b}{a} implies f(0) = dfrac{b}{0} = text{undefined} $$



However, directly determining $f(0)$ makes no sense in this case. Could you assist me with that?










share|cite|improve this question




















  • 1




    Substitute $x=dfrac{-b}{a}$.
    – Yadati Kiran
    Nov 25 at 17:14












  • Surely $a$ is a constant here and not a variable?
    – Mark Bennet
    Nov 25 at 17:16










  • @Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
    – Rebellos
    Nov 25 at 17:19












  • @Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
    – Enzo
    Nov 25 at 17:19












  • @Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
    – Rebellos
    Nov 25 at 17:22













up vote
-1
down vote

favorite









up vote
-1
down vote

favorite











$$f(ax+b) = x$$
$$f(a) = dfrac{b}{a}$$



I want to determine $f(0)$ from given equations.



My attempt:



$$f(a)= dfrac{b}{a} implies f(0) = dfrac{b}{0} = text{undefined} $$



However, directly determining $f(0)$ makes no sense in this case. Could you assist me with that?










share|cite|improve this question















$$f(ax+b) = x$$
$$f(a) = dfrac{b}{a}$$



I want to determine $f(0)$ from given equations.



My attempt:



$$f(a)= dfrac{b}{a} implies f(0) = dfrac{b}{0} = text{undefined} $$



However, directly determining $f(0)$ makes no sense in this case. Could you assist me with that?







functions






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share|cite|improve this question













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share|cite|improve this question








edited Nov 25 at 17:14

























asked Nov 25 at 17:12









Enzo

926




926








  • 1




    Substitute $x=dfrac{-b}{a}$.
    – Yadati Kiran
    Nov 25 at 17:14












  • Surely $a$ is a constant here and not a variable?
    – Mark Bennet
    Nov 25 at 17:16










  • @Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
    – Rebellos
    Nov 25 at 17:19












  • @Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
    – Enzo
    Nov 25 at 17:19












  • @Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
    – Rebellos
    Nov 25 at 17:22














  • 1




    Substitute $x=dfrac{-b}{a}$.
    – Yadati Kiran
    Nov 25 at 17:14












  • Surely $a$ is a constant here and not a variable?
    – Mark Bennet
    Nov 25 at 17:16










  • @Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
    – Rebellos
    Nov 25 at 17:19












  • @Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
    – Enzo
    Nov 25 at 17:19












  • @Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
    – Rebellos
    Nov 25 at 17:22








1




1




Substitute $x=dfrac{-b}{a}$.
– Yadati Kiran
Nov 25 at 17:14






Substitute $x=dfrac{-b}{a}$.
– Yadati Kiran
Nov 25 at 17:14














Surely $a$ is a constant here and not a variable?
– Mark Bennet
Nov 25 at 17:16




Surely $a$ is a constant here and not a variable?
– Mark Bennet
Nov 25 at 17:16












@Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
– Rebellos
Nov 25 at 17:19






@Enzo Not possible to find a numberical value from the facts given. Also, if $a$ is a constant then using $a=0$ is wrong. You must determine $f(0)$ from the initial expression.
– Rebellos
Nov 25 at 17:19














@Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
– Enzo
Nov 25 at 17:19






@Rebellos Assume that $a, b neq 0 in mathcal{R}$, Is it the same in this case?
– Enzo
Nov 25 at 17:19














@Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
– Rebellos
Nov 25 at 17:22




@Enzo Yes. Also if you want to typeset the set of real numbers, try mathbb R which produces $mathbb R$.
– Rebellos
Nov 25 at 17:22










3 Answers
3






active

oldest

votes

















up vote
0
down vote



accepted










By the way upon computing, the function is $f(x)=dfrac{b(2x-a)}{a^2}$ and $f(0)=dfrac{-b}{a}$. Further using $f(ax+b)=x$ we get $b=dfrac{a}{2}$. So the function is $f(x)=dfrac{2x-a}{2a}$ and $f(0)=dfrac{-1}{2}$, $f(a)=dfrac{1}{2}$.






share|cite|improve this answer






























    up vote
    1
    down vote













    Well, you want the argument of your given function to be equal to zero. Thus, considering the argument of the funtion $f(ax+b) = x$, we have :



    $$ax + b = 0 Leftrightarrow x = -frac{b}{a}$$



    Then, $f(0)$ would be yielded for $x= -b/a$, thus again by substituting in the first function expression :



    $$f(0)=-frac{b}{a}=-f(a)$$






    share|cite|improve this answer





















    • But is it possible to find a numerical value?
      – Enzo
      Nov 25 at 17:17










    • @Enzo No, since all your given expressions involve arbitrary constants.
      – Rebellos
      Nov 25 at 17:18


















    up vote
    1
    down vote













    Here is a start - and contrary to comments, there is a solution.



    Let $y=ax+b$ so that $f(y)=x=cfrac {y-b}a$ so now we have expressed $f$ as a linear function of its argument.



    I have not yet used the value for $f(a)$ that has been given, so this is the next step.






    share|cite|improve this answer





















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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      0
      down vote



      accepted










      By the way upon computing, the function is $f(x)=dfrac{b(2x-a)}{a^2}$ and $f(0)=dfrac{-b}{a}$. Further using $f(ax+b)=x$ we get $b=dfrac{a}{2}$. So the function is $f(x)=dfrac{2x-a}{2a}$ and $f(0)=dfrac{-1}{2}$, $f(a)=dfrac{1}{2}$.






      share|cite|improve this answer



























        up vote
        0
        down vote



        accepted










        By the way upon computing, the function is $f(x)=dfrac{b(2x-a)}{a^2}$ and $f(0)=dfrac{-b}{a}$. Further using $f(ax+b)=x$ we get $b=dfrac{a}{2}$. So the function is $f(x)=dfrac{2x-a}{2a}$ and $f(0)=dfrac{-1}{2}$, $f(a)=dfrac{1}{2}$.






        share|cite|improve this answer

























          up vote
          0
          down vote



          accepted







          up vote
          0
          down vote



          accepted






          By the way upon computing, the function is $f(x)=dfrac{b(2x-a)}{a^2}$ and $f(0)=dfrac{-b}{a}$. Further using $f(ax+b)=x$ we get $b=dfrac{a}{2}$. So the function is $f(x)=dfrac{2x-a}{2a}$ and $f(0)=dfrac{-1}{2}$, $f(a)=dfrac{1}{2}$.






          share|cite|improve this answer














          By the way upon computing, the function is $f(x)=dfrac{b(2x-a)}{a^2}$ and $f(0)=dfrac{-b}{a}$. Further using $f(ax+b)=x$ we get $b=dfrac{a}{2}$. So the function is $f(x)=dfrac{2x-a}{2a}$ and $f(0)=dfrac{-1}{2}$, $f(a)=dfrac{1}{2}$.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Nov 25 at 17:47

























          answered Nov 25 at 17:39









          Yadati Kiran

          1,298417




          1,298417






















              up vote
              1
              down vote













              Well, you want the argument of your given function to be equal to zero. Thus, considering the argument of the funtion $f(ax+b) = x$, we have :



              $$ax + b = 0 Leftrightarrow x = -frac{b}{a}$$



              Then, $f(0)$ would be yielded for $x= -b/a$, thus again by substituting in the first function expression :



              $$f(0)=-frac{b}{a}=-f(a)$$






              share|cite|improve this answer





















              • But is it possible to find a numerical value?
                – Enzo
                Nov 25 at 17:17










              • @Enzo No, since all your given expressions involve arbitrary constants.
                – Rebellos
                Nov 25 at 17:18















              up vote
              1
              down vote













              Well, you want the argument of your given function to be equal to zero. Thus, considering the argument of the funtion $f(ax+b) = x$, we have :



              $$ax + b = 0 Leftrightarrow x = -frac{b}{a}$$



              Then, $f(0)$ would be yielded for $x= -b/a$, thus again by substituting in the first function expression :



              $$f(0)=-frac{b}{a}=-f(a)$$






              share|cite|improve this answer





















              • But is it possible to find a numerical value?
                – Enzo
                Nov 25 at 17:17










              • @Enzo No, since all your given expressions involve arbitrary constants.
                – Rebellos
                Nov 25 at 17:18













              up vote
              1
              down vote










              up vote
              1
              down vote









              Well, you want the argument of your given function to be equal to zero. Thus, considering the argument of the funtion $f(ax+b) = x$, we have :



              $$ax + b = 0 Leftrightarrow x = -frac{b}{a}$$



              Then, $f(0)$ would be yielded for $x= -b/a$, thus again by substituting in the first function expression :



              $$f(0)=-frac{b}{a}=-f(a)$$






              share|cite|improve this answer












              Well, you want the argument of your given function to be equal to zero. Thus, considering the argument of the funtion $f(ax+b) = x$, we have :



              $$ax + b = 0 Leftrightarrow x = -frac{b}{a}$$



              Then, $f(0)$ would be yielded for $x= -b/a$, thus again by substituting in the first function expression :



              $$f(0)=-frac{b}{a}=-f(a)$$







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered Nov 25 at 17:17









              Rebellos

              13.3k21142




              13.3k21142












              • But is it possible to find a numerical value?
                – Enzo
                Nov 25 at 17:17










              • @Enzo No, since all your given expressions involve arbitrary constants.
                – Rebellos
                Nov 25 at 17:18


















              • But is it possible to find a numerical value?
                – Enzo
                Nov 25 at 17:17










              • @Enzo No, since all your given expressions involve arbitrary constants.
                – Rebellos
                Nov 25 at 17:18
















              But is it possible to find a numerical value?
              – Enzo
              Nov 25 at 17:17




              But is it possible to find a numerical value?
              – Enzo
              Nov 25 at 17:17












              @Enzo No, since all your given expressions involve arbitrary constants.
              – Rebellos
              Nov 25 at 17:18




              @Enzo No, since all your given expressions involve arbitrary constants.
              – Rebellos
              Nov 25 at 17:18










              up vote
              1
              down vote













              Here is a start - and contrary to comments, there is a solution.



              Let $y=ax+b$ so that $f(y)=x=cfrac {y-b}a$ so now we have expressed $f$ as a linear function of its argument.



              I have not yet used the value for $f(a)$ that has been given, so this is the next step.






              share|cite|improve this answer

























                up vote
                1
                down vote













                Here is a start - and contrary to comments, there is a solution.



                Let $y=ax+b$ so that $f(y)=x=cfrac {y-b}a$ so now we have expressed $f$ as a linear function of its argument.



                I have not yet used the value for $f(a)$ that has been given, so this is the next step.






                share|cite|improve this answer























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  Here is a start - and contrary to comments, there is a solution.



                  Let $y=ax+b$ so that $f(y)=x=cfrac {y-b}a$ so now we have expressed $f$ as a linear function of its argument.



                  I have not yet used the value for $f(a)$ that has been given, so this is the next step.






                  share|cite|improve this answer












                  Here is a start - and contrary to comments, there is a solution.



                  Let $y=ax+b$ so that $f(y)=x=cfrac {y-b}a$ so now we have expressed $f$ as a linear function of its argument.



                  I have not yet used the value for $f(a)$ that has been given, so this is the next step.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Nov 25 at 17:35









                  Mark Bennet

                  80.1k981179




                  80.1k981179






























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