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February 25th, 2017, 08:00 PM  #1 
Newbie Joined: Feb 2017 From: Canada Posts: 3 Thanks: 0  x intercept with cosine and natural log equations
I've got a math question I'm trying to figure out, but it's been so long since I studied math that it's all a blur now. Any help or guidance would be great. You can probably tell by my username how long ago all this was... Find the x intercept where y = e^cos x and y = x * ln x 
February 25th, 2017, 08:02 PM  #2 
Senior Member Joined: Feb 2016 From: Australia Posts: 1,634 Thanks: 567 Math Focus: Yet to find out.  
February 25th, 2017, 08:03 PM  #3 
Senior Member Joined: Aug 2012 Posts: 1,999 Thanks: 573 
The xintercept is the point where y = 0. Since the exponential function is never zero, e^cos x has no xintercept. Did you mean the point of intersection of the two graphs? 
February 25th, 2017, 08:32 PM  #4 
Newbie Joined: Feb 2017 From: Canada Posts: 3 Thanks: 0 
Sorry, I meant find the x coordinate of the point of intersection of the two y equations. I tried that Wolframalpha, but it said the computation time was exceeded so going Pro would be needed. Maybe some direction and pointers would be good. I was Googling e and log functions and how to factor them down which looked familiar, but that cosine of x is throwing things off I think. 
February 25th, 2017, 08:34 PM  #5  
Senior Member Joined: Sep 2015 From: USA Posts: 2,091 Thanks: 1087  Quote:
The solution is $x \approx 1.69$  
February 25th, 2017, 08:59 PM  #6 
Newbie Joined: Feb 2017 From: Canada Posts: 3 Thanks: 0 
Oops I didn't click the link. I was at that Wolfram site previously and entered the two equations, but I see the link provided does work. I must have entered them incorrectly. I didn't put brackets around cos x. Could you show me the work involved in getting to the x calculation?
Last edited by sothirtyyearsago; February 25th, 2017 at 09:02 PM. 
February 25th, 2017, 09:06 PM  #7  
Senior Member Joined: Sep 2015 From: USA Posts: 2,091 Thanks: 1087  Quote:
Here is one example of a commonly used numeric method.  

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cosine, equations, intercept, log, natural 
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