Mathematics
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OpenStudy (mathmusician):
Integration
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OpenStudy (mathmusician):
For a continuous function f(x), f(1)=11, and \[\int\limits_{1}^{5}f'(x)dx = 9\] determine f(5).
OpenStudy (mathmusician):
@freckles
OpenStudy (freckles):
do you know what
\[\int\limits f'(x) dx=?\]
OpenStudy (mathmusician):
9
OpenStudy (mathmusician):
oh wait that is the indefinte integral
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OpenStudy (freckles):
that isn't what i'm asking
your question has definite integral in it while I asked about indefinite integral
OpenStudy (freckles):
ok you got it :p
OpenStudy (freckles):
I mean you figured out I was asking about a indefinite integral
OpenStudy (mathmusician):
F(x)
OpenStudy (freckles):
you do know the derivative of f(x) is f'(x)
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OpenStudy (freckles):
so the integral of f'(x) is f(x)+C
OpenStudy (freckles):
\[\int\limits f'(x) dx=f(x)+C\]
OpenStudy (freckles):
in definite integrals we don't need the C since they get cancel out in the simplifcation of a definite integral
OpenStudy (freckles):
\[\int\limits_a^b f'(x) dx=f(x)|_a^b =f(b)-f(a)\]
OpenStudy (freckles):
can you show me your equation you have after evaluating your definite integral on your left hand side of your equation you wrote
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OpenStudy (mathmusician):
The left-hand side like Reiman sums?
OpenStudy (freckles):
no no
OpenStudy (freckles):
you have an equation
OpenStudy (freckles):
for example a=b
the right hand expression of the equation is b
and left hand expression of the equation is a
OpenStudy (mathmusician):
Oh duh
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OpenStudy (freckles):
your left hand side looks like this
\[\int\limits_1^5 f'(x)\]
OpenStudy (freckles):
I'm asking you to evaluate the definite integral here
OpenStudy (mathmusician):
we dont have f'(x) though
OpenStudy (freckles):
here is a hint:
\[\int\limits_1^5 f'(x) dx=f(x)|_1^5=....\]
OpenStudy (mathmusician):
9 right?
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OpenStudy (freckles):
don't look at the right hand side yet
OpenStudy (freckles):
I'm trying to get you the write the left hand side as f(5)-f(1)
OpenStudy (mathmusician):
4
OpenStudy (freckles):
f(5)-f(1)=9
you are given f(1)=11
f(5)-11=9
solve for f(5)
OpenStudy (mathmusician):
oh yah now i remember this
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OpenStudy (freckles):
you are going to add what to both sides to do this?
OpenStudy (mathmusician):
20
OpenStudy (freckles):
yes f(5)=11+9
f(5)=20
OpenStudy (freckles):
do you have any questions on this one
(I'm going to leave you if you don't)
OpenStudy (mathmusician):
My computer hit a lag spike
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OpenStudy (mathmusician):
okay im good thanks
OpenStudy (mathmusician):
enjoy your lunch
OpenStudy (freckles):
I think I seen @zepdrix on
he is really good at math too
OpenStudy (freckles):
Peace
OpenStudy (mathmusician):
Yup im a fan