- #1

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y= f'(a)(x-a)+b this must mean that

f'(a) = (y-b)/(x-a)

But that to me seems troubeling, because f'(a) is the slope at ONE point, while (y-b)/(x-a) is a quotient with the differene between 2 points. Is there a better explanation?

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- Thread starter christian0710
- Start date

- #1

- 409

- 9

y= f'(a)(x-a)+b this must mean that

f'(a) = (y-b)/(x-a)

But that to me seems troubeling, because f'(a) is the slope at ONE point, while (y-b)/(x-a) is a quotient with the differene between 2 points. Is there a better explanation?

- #2

HallsofIvy

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- #3

RUber

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(y-b)/(x-a) is 0/0 at (a,b), so might not be the best form to use...although it does give some insight to L'Hopital's rule.

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