question on function and image












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$begingroup$


Consider $f: R^2-> R$ given by
$f(v,w)=(v+w)/2 +|v-w|/2$



We also had to show that $g=f$ where $g: R^2-> R$ given by



g(v,w)= v if v>=w and w if v<0



Derive with proof the image of [0,1] times [-1,1] under f.



Quite stuck with this question i think i have figured out that the image is [0,1] but not sure. Then you have to prove this so something to do with showing f([0,1] times [-1,1]) is a subset of [0,1] and show the other way but no idea reall yhow to do this. Thanks for help in advance



im ok with the g=f part just need help with the image part.










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$endgroup$

















    0












    $begingroup$


    Consider $f: R^2-> R$ given by
    $f(v,w)=(v+w)/2 +|v-w|/2$



    We also had to show that $g=f$ where $g: R^2-> R$ given by



    g(v,w)= v if v>=w and w if v<0



    Derive with proof the image of [0,1] times [-1,1] under f.



    Quite stuck with this question i think i have figured out that the image is [0,1] but not sure. Then you have to prove this so something to do with showing f([0,1] times [-1,1]) is a subset of [0,1] and show the other way but no idea reall yhow to do this. Thanks for help in advance



    im ok with the g=f part just need help with the image part.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Consider $f: R^2-> R$ given by
      $f(v,w)=(v+w)/2 +|v-w|/2$



      We also had to show that $g=f$ where $g: R^2-> R$ given by



      g(v,w)= v if v>=w and w if v<0



      Derive with proof the image of [0,1] times [-1,1] under f.



      Quite stuck with this question i think i have figured out that the image is [0,1] but not sure. Then you have to prove this so something to do with showing f([0,1] times [-1,1]) is a subset of [0,1] and show the other way but no idea reall yhow to do this. Thanks for help in advance



      im ok with the g=f part just need help with the image part.










      share|cite|improve this question











      $endgroup$




      Consider $f: R^2-> R$ given by
      $f(v,w)=(v+w)/2 +|v-w|/2$



      We also had to show that $g=f$ where $g: R^2-> R$ given by



      g(v,w)= v if v>=w and w if v<0



      Derive with proof the image of [0,1] times [-1,1] under f.



      Quite stuck with this question i think i have figured out that the image is [0,1] but not sure. Then you have to prove this so something to do with showing f([0,1] times [-1,1]) is a subset of [0,1] and show the other way but no idea reall yhow to do this. Thanks for help in advance



      im ok with the g=f part just need help with the image part.







      functions






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      share|cite|improve this question













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      edited Dec 3 '18 at 23:44







      Harry

















      asked Dec 3 '18 at 23:38









      HarryHarry

      253




      253






















          2 Answers
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          $begingroup$

          The definition of $f(v,w)$ suggests that it is just the maximum of $v$ and $w$



          The image is $[0,1] $ because you can simply pick $v=0$ and run $w$ over $[0,1]$






          share|cite|improve this answer









          $endgroup$





















            0












            $begingroup$

            Consider the cases $v geq w$ and $v<w$. In the first case $|v-w|=v-w$ so $f(v,w)=v$ and in the second case $|v-w|=w-v$ so $f(v,w)=w$. This proves that $f=g$. Note that $|x|+x geq 0$ for any real number $x$. Hence $f$ takes only non-negative values. From the form of $g$ it follows that the image is contained in $[0,1]$. To show that the image is all of $[0,1]$ just note that $g(t,0)=t$ for all $t in [0,1]$.






            share|cite|improve this answer









            $endgroup$













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              2 Answers
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              2 Answers
              2






              active

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              active

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              0












              $begingroup$

              The definition of $f(v,w)$ suggests that it is just the maximum of $v$ and $w$



              The image is $[0,1] $ because you can simply pick $v=0$ and run $w$ over $[0,1]$






              share|cite|improve this answer









              $endgroup$


















                0












                $begingroup$

                The definition of $f(v,w)$ suggests that it is just the maximum of $v$ and $w$



                The image is $[0,1] $ because you can simply pick $v=0$ and run $w$ over $[0,1]$






                share|cite|improve this answer









                $endgroup$
















                  0












                  0








                  0





                  $begingroup$

                  The definition of $f(v,w)$ suggests that it is just the maximum of $v$ and $w$



                  The image is $[0,1] $ because you can simply pick $v=0$ and run $w$ over $[0,1]$






                  share|cite|improve this answer









                  $endgroup$



                  The definition of $f(v,w)$ suggests that it is just the maximum of $v$ and $w$



                  The image is $[0,1] $ because you can simply pick $v=0$ and run $w$ over $[0,1]$







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Dec 3 '18 at 23:57









                  Mohammad Riazi-KermaniMohammad Riazi-Kermani

                  41.5k42061




                  41.5k42061























                      0












                      $begingroup$

                      Consider the cases $v geq w$ and $v<w$. In the first case $|v-w|=v-w$ so $f(v,w)=v$ and in the second case $|v-w|=w-v$ so $f(v,w)=w$. This proves that $f=g$. Note that $|x|+x geq 0$ for any real number $x$. Hence $f$ takes only non-negative values. From the form of $g$ it follows that the image is contained in $[0,1]$. To show that the image is all of $[0,1]$ just note that $g(t,0)=t$ for all $t in [0,1]$.






                      share|cite|improve this answer









                      $endgroup$


















                        0












                        $begingroup$

                        Consider the cases $v geq w$ and $v<w$. In the first case $|v-w|=v-w$ so $f(v,w)=v$ and in the second case $|v-w|=w-v$ so $f(v,w)=w$. This proves that $f=g$. Note that $|x|+x geq 0$ for any real number $x$. Hence $f$ takes only non-negative values. From the form of $g$ it follows that the image is contained in $[0,1]$. To show that the image is all of $[0,1]$ just note that $g(t,0)=t$ for all $t in [0,1]$.






                        share|cite|improve this answer









                        $endgroup$
















                          0












                          0








                          0





                          $begingroup$

                          Consider the cases $v geq w$ and $v<w$. In the first case $|v-w|=v-w$ so $f(v,w)=v$ and in the second case $|v-w|=w-v$ so $f(v,w)=w$. This proves that $f=g$. Note that $|x|+x geq 0$ for any real number $x$. Hence $f$ takes only non-negative values. From the form of $g$ it follows that the image is contained in $[0,1]$. To show that the image is all of $[0,1]$ just note that $g(t,0)=t$ for all $t in [0,1]$.






                          share|cite|improve this answer









                          $endgroup$



                          Consider the cases $v geq w$ and $v<w$. In the first case $|v-w|=v-w$ so $f(v,w)=v$ and in the second case $|v-w|=w-v$ so $f(v,w)=w$. This proves that $f=g$. Note that $|x|+x geq 0$ for any real number $x$. Hence $f$ takes only non-negative values. From the form of $g$ it follows that the image is contained in $[0,1]$. To show that the image is all of $[0,1]$ just note that $g(t,0)=t$ for all $t in [0,1]$.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered Dec 3 '18 at 23:57









                          Kavi Rama MurthyKavi Rama Murthy

                          55.7k42158




                          55.7k42158






























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