Slope of graph?

DEVEREUX · 2012-05-21 19:20:44

I have an exam looming and have hit a speed bump with the following question find slope of graph y = 1/x when x = 2 What im getting is 1/x = x^-1 giving me 2^-1 = - 1/2 Above makes sense to me but in the answer sheet for this particular question the lecturer has the answer as -1/4 ???? Help appreciated, thanks.

21-05-2012 08:20PM

#1

DEVEREUX

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I have an exam looming and have hit a speed bump with the following question

find slope of graph y = 1/x when x = 2

What im getting is

1/x = x^-1

giving me

2^-1 = - 1/2

Above makes sense to me but in the answer sheet for this particular question the lecturer has the answer as -1/4 ????
Help appreciated, thanks.

0

Comments

#2 21-05-2012 08:24PM

**Timbuk2**

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You have [latex]y = x^{-1}[/latex]

The slope is the derivative, i.e. [latex]\frac{dy}{dx} = \frac{d}{dx}x^{-1} = -\frac{1}{x^2}[/latex]

At x=2, this is -1/4

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#3 21-05-2012 08:50PM

DEVEREUX

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Join Date: September 2008

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**Timbuk2** wrote: »

You have [latex]y = x^{-1}[/latex]

The slope is the derivative, i.e. [latex]\frac{dy}{dx} = \frac{d}{dx}x^{-1} = -\frac{1}{x^2}[/latex]

At x=2, this is -1/4

Thanks for that.

0