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anonymous
 5 years ago
find the equation of the tangent line to the curve when x has the given value... f(x)= 5x^2+x ; x=4
anonymous
 5 years ago
find the equation of the tangent line to the curve when x has the given value... f(x)= 5x^2+x ; x=4

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anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0You have to find the gradient function of f first. This will give you the gradient at any point. Then you need to use the pointgradient formula for a straight line. The point you'll be using is the point where the tangent touches the parabola (since a tangent only touches at one point). So the point here is x=4, f(4) = 5(4)^2+(4) = 76; i.e (4,76). Your gradient is \[f'(x)=10x+1 \rightarrow f'(4)=40+1 = 39\]The equation of the tangent line is then\[y76=39(x(4)) \rightarrow y = 39x80\]

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Recheck everything  I just saw this question unanswered and stole some time. The theory is right, though :)

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0yeah that's right thank u:) i just couldnt figure out the steps
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