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Problem with equation of line tangent to curve

  • Thread starter Chas3down
  • Start date
  • #1
60
0

Homework Statement


Now use your answer from part (a)(This anwser is f'(25) = 7/10, which is correct) to find the equation of the tangent line to the curve at the point (25, f(25)).


Homework Equations


f(x) = 7*sqrt(x)+3



The Attempt at a Solution


f'(25) = 7/10
f(25) = 38
y=mx+b
38=7/10*25+b

y=7/10x + 41/2

This should be the correct answer... but it won't accept it.


if you want to view the entire problem, http://i.imgur.com/xtVehti.png
 

Answers and Replies

  • #2
185
4
Try using something other than y=mx+b. Do you know any other ways to write the equation that doesn't rely on B?
 
  • #3
60
0
Try using something other than y=mx+b. Do you know any other ways to write the equation that doesn't rely on B?
we are given y= ???

so y=mx+b is really the only linear function they could be looking for.
 
  • #4
185
4
Try y-y_1=m(x-x_1). You are given y_1 and x_1 (or can easily find them) and you have already solved for m. The rest is plugging in and simplifying.
 
  • #5
60
0
Try y-y_1=m(x-x_1). You are given y_1 and x_1 (or can easily find them) and you have already solved for m. The rest is plugging in and simplifying.
edit: i am an idiot... had a - instead of a +
 

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