# given a tangent line, find f(x)

by mbrmbrg
Tags: line, tangent
 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 point-slope 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!
 P: 927 You don't need f(x) to know what f(4) is. You're already given f(4)
 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...
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## given a tangent line, find f(x)

 Quote by mbrmbrg Thank you! I have to remember that learning calculus does not mean forgetting the very first rules of reading ordered pairs, don't I...
Well put!
 P: 1 what will be f'(4)? 0?

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