Find an equation of the tangent line of the exponential function at the point (0,1)












1












$begingroup$


So I differentiated the expression
$$ y=e^{2x}cos(pi x) $$
And I got
$$ y'=2e^{2x}cos(pi x)-pi e^{2x}sin(pi x)$$
But when from the given point $(0,1)$ when I plug in zero I get 2



I looked the answer up in the back of my textbook (which I know I shouldn't do) and the answer is $y=2x+1$










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$endgroup$












  • $begingroup$
    $y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
    $endgroup$
    – Anurag A
    Dec 11 '18 at 2:28












  • $begingroup$
    I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
    $endgroup$
    – T. Bongers
    Dec 11 '18 at 2:30
















1












$begingroup$


So I differentiated the expression
$$ y=e^{2x}cos(pi x) $$
And I got
$$ y'=2e^{2x}cos(pi x)-pi e^{2x}sin(pi x)$$
But when from the given point $(0,1)$ when I plug in zero I get 2



I looked the answer up in the back of my textbook (which I know I shouldn't do) and the answer is $y=2x+1$










share|cite|improve this question











$endgroup$












  • $begingroup$
    $y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
    $endgroup$
    – Anurag A
    Dec 11 '18 at 2:28












  • $begingroup$
    I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
    $endgroup$
    – T. Bongers
    Dec 11 '18 at 2:30














1












1








1





$begingroup$


So I differentiated the expression
$$ y=e^{2x}cos(pi x) $$
And I got
$$ y'=2e^{2x}cos(pi x)-pi e^{2x}sin(pi x)$$
But when from the given point $(0,1)$ when I plug in zero I get 2



I looked the answer up in the back of my textbook (which I know I shouldn't do) and the answer is $y=2x+1$










share|cite|improve this question











$endgroup$




So I differentiated the expression
$$ y=e^{2x}cos(pi x) $$
And I got
$$ y'=2e^{2x}cos(pi x)-pi e^{2x}sin(pi x)$$
But when from the given point $(0,1)$ when I plug in zero I get 2



I looked the answer up in the back of my textbook (which I know I shouldn't do) and the answer is $y=2x+1$







calculus exponential-function






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 11 '18 at 2:33









Dando18

4,68241235




4,68241235










asked Dec 11 '18 at 2:26









Eric BrownEric Brown

757




757












  • $begingroup$
    $y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
    $endgroup$
    – Anurag A
    Dec 11 '18 at 2:28












  • $begingroup$
    I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
    $endgroup$
    – T. Bongers
    Dec 11 '18 at 2:30


















  • $begingroup$
    $y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
    $endgroup$
    – Anurag A
    Dec 11 '18 at 2:28












  • $begingroup$
    I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
    $endgroup$
    – T. Bongers
    Dec 11 '18 at 2:30
















$begingroup$
$y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
$endgroup$
– Anurag A
Dec 11 '18 at 2:28






$begingroup$
$y'(0)=2$ gives you the slope of the line at $(0,1)$. You still need to find the equation of the line (given it's slope and a point lying on it).
$endgroup$
– Anurag A
Dec 11 '18 at 2:28














$begingroup$
I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
$endgroup$
– T. Bongers
Dec 11 '18 at 2:30




$begingroup$
I think this might be a case where you're not sure what you're actually looking for. You say you get $2$, which is indeed $y'(0)$. But you're not looking for a number, you're looking for a line.
$endgroup$
– T. Bongers
Dec 11 '18 at 2:30










1 Answer
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$begingroup$

You are looking for a line $(y-y_0)=m(x-x_0)$, where $(x_0,y_0)$ is a point on the line and $m$ is the slope of the line.



You are correct in finding the derivative, since $m=y'(0)$. That is, the derivative at $x_0$ is the slope of the tangent line at $x_0$. So now you just have to use the point given to find the equation of the line,



$$ (y-1) = 2(x-0) implies y=2x+1 $$






share|cite|improve this answer









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    1 Answer
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    1 Answer
    1






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    0












    $begingroup$

    You are looking for a line $(y-y_0)=m(x-x_0)$, where $(x_0,y_0)$ is a point on the line and $m$ is the slope of the line.



    You are correct in finding the derivative, since $m=y'(0)$. That is, the derivative at $x_0$ is the slope of the tangent line at $x_0$. So now you just have to use the point given to find the equation of the line,



    $$ (y-1) = 2(x-0) implies y=2x+1 $$






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      You are looking for a line $(y-y_0)=m(x-x_0)$, where $(x_0,y_0)$ is a point on the line and $m$ is the slope of the line.



      You are correct in finding the derivative, since $m=y'(0)$. That is, the derivative at $x_0$ is the slope of the tangent line at $x_0$. So now you just have to use the point given to find the equation of the line,



      $$ (y-1) = 2(x-0) implies y=2x+1 $$






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        You are looking for a line $(y-y_0)=m(x-x_0)$, where $(x_0,y_0)$ is a point on the line and $m$ is the slope of the line.



        You are correct in finding the derivative, since $m=y'(0)$. That is, the derivative at $x_0$ is the slope of the tangent line at $x_0$. So now you just have to use the point given to find the equation of the line,



        $$ (y-1) = 2(x-0) implies y=2x+1 $$






        share|cite|improve this answer









        $endgroup$



        You are looking for a line $(y-y_0)=m(x-x_0)$, where $(x_0,y_0)$ is a point on the line and $m$ is the slope of the line.



        You are correct in finding the derivative, since $m=y'(0)$. That is, the derivative at $x_0$ is the slope of the tangent line at $x_0$. So now you just have to use the point given to find the equation of the line,



        $$ (y-1) = 2(x-0) implies y=2x+1 $$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 11 '18 at 2:37









        Dando18Dando18

        4,68241235




        4,68241235






























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