area under a graph

J

jay1234

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Nov 7, 2006
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How do I get started on this question f(x)=1/x on [1,8]

how can I find the area under the graph. My book isn't very clear on that. So far I got:

ln[x] | on [1,8] I don't know where to go from there. Note, I can't do the stick thing with the 1 at the bottom and the 8 at the top of the stick. thanks.
 
your book does not have the Fundamental Theorm of Calculus in it?
hmmmm.....

try looking that up...
 
I see something like ∫f(x)dx=F(b)-F(a)

but I don't know what to do with it. Like I said, my book isn't very clear on it. It has proofs, but not good at samples.
 
the F(b) - F(a) is the antiderivative you found evaluated at the end point of the interval [1,8]
 
here is an example

find the area under x^2 from [1,4]

the antiderivative is (1/3)x^3

so the area under it is

(1/3)(4)^3 - (1/3)(1)^3 = Area
 
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