- #1

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I've no clue at all...

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- Thread starter danne89
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- #1

- 180

- 0

I've no clue at all...

- #2

HallsofIvy

Science Advisor

Homework Helper

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4= 2

Has no one told you that the derivative at a point IS the slope of the tangent line at that point? What is the slope of the line y= 2x? Can you find the derivative of

y= x

- #3

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You have y = 2x as the tangent line.. and you know that y' = 2x + b and thus you can substitute x = 2 into y' to get y' = 4 + b and from the question you know y' = 2... and so 2 = 4 + b; b = -2danne89 said:

I've no clue at all...

Next step is finding c, just plug in:

4 = 4 - 4 + c

c = 4

And the parabola is y = x^2 - 2x + 4

And to test it..

y' = 2x - 2

And at the point (2,4); y - 4 = 2(x-2); y = 2x - 4 + 4 = 2x

And that's the answer...

Or I could be completely wrong.

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