Register to reply 
Given a tangent line, find f(x) 
Share this thread: 
#1
Jul1006, 11:32 AM

P: 497

I have a homework problem as follows:
If the tangent line to y = f(x) at (4,3) passes through the point (0,2), find f(4) and f'(4). Using the slope formula and the pointslope formula, I found that the equation of the given tangent line is y = 1/4x + 2. Now I want to find f(x) so I can actually answer the question. I thought I might be able to solve for f(x) using the equation f'(a)= lim [f(x+h)  f(x)]/h h>0 and subsituting 1/4 for f'(a), but I can't get any farther than setting that up. help? please? thanks! 


#2
Jul1006, 11:53 AM

P: 926

You don't need f(x) to know what f(4) is. You're already given f(4)



#3
Jul1006, 11:55 AM

P: 497

Thank you!
I have to remember that learning calculus does not mean forgetting the very first rules of reading ordered pairs, don't I... 


#4
Jul1006, 03:14 PM

Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,323

Given a tangent line, find f(x)



#5
Oct908, 03:09 PM

P: 1

what will be f'(4)?
0? 


Register to reply 
Related Discussions  
Find an equation of the tangent line to the curve at the given point  Calculus & Beyond Homework  23  
Find the equation of tangent line  Calculus & Beyond Homework  2  
Find equation of tangent line  Calculus & Beyond Homework  3  
Find the equation of a tangent line to y=f(x)  Calculus & Beyond Homework  3  
Find k such that the line is tangent to the graph  Calculus  5 