Posted by dino on Monday, November 5, 2012 at 8:51pm.
Show that the tanget lines to the graph of Y= e^x  e^x /e^x + e^x at x =1 and x= 1 are parallel.
I know to use the Quotient rule but I am having a hard time with this problem.

calculus  Steve, Monday, November 5, 2012 at 9:17pm
y = tanh(x)
there are asymptotes at y=1 and y=1
just consider when x gets large positive. e^x vanishes, and you have e^x/e^x = 1
when x gets large negative, e^x vanishes, and you have e^x/e^1 = 1

calculus  Reiny, Monday, November 5, 2012 at 9:30pm
first of all simplify it a bit,
multiplying top and bottom by e^x to get
y = (e^(2x) 1)/(e^(2x) + 1)
dy/dx = [(e^(2x) + 1)(2e^(2x))  (e^(2x) 1)(2e^(2x)) )/(e^(2x) + 1)^2
= 2e^(2x)(e^(2x) + 1 + e^(2x)  1)/(e^(2x+1)^2
= 4e^(2x)/(e^(2x)+1)^2
confirmed by Wolfram:
http://www.wolframalpha.com/input/?i=derivative+of+%28e^x++e^x%29%2F%28e^x+%2B+e^x%29
I will leave it up to you to sub in x=1 and x=1 to show that you get the same value, I did.

calculus  dino, Monday, November 5, 2012 at 9:35pm
thank you very Much
Answer This Question
Related Questions
 Calculus  How do I use the chain rule to find the derivative of square root(1x...
 Calculus  The graph of the equation x2 − xy + y2 = 9 is an ellipse. Find ...
 Calculus  Let f(x)= 5x  x–2 are we supposed to use the quotient rule? ...
 Calculus  I'm having problems with this one. Can't get the right answer. ...
 calculus  find one point on the graph of y= x+2cosx such that the tanget is ...
 Calculus  f(x)=5+(6/x)+(7/x^2), find f'(x). I haven't done fractions without ...
 Technology  When using a line graph, why is it inportant to only graph 1  3 ...
 MATH PLS HELP CHECK ANSWERS  3. What is the rule for the function shown in the ...
 Geometry  Solve for x 5/3 / 4/3 = x / 20/9 x= 25/9 =2.77777.... 5/4 = x/3 x= 15...
 Geometry  Solve for x x/6 = x+1 / 9 x= 2 Tell whether the lines are parallel ...
More Related Questions