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OpenStudy (anonymous):

Integral question see attached images

OpenStudy (anonymous):

OpenStudy (anonymous):

OpenStudy (anonymous):

I'm not really sure how to do this I did the anti-derivative for both of fx then used the 1st fund thrm of calc

OpenStudy (turingtest):

just break it into two integrals what are the bounds? where is the breaking point in the function?

OpenStudy (anonymous):

hmm and just do f(b)-f(a) for both? and add them together?

OpenStudy (turingtest):

what do f(a) oand f(b) represent to you? I don't see how that way of writing things helps us...

OpenStudy (anonymous):

F(b)-F(a) b being the top value and a being the bottom value listed on the integral

OpenStudy (anonymous):

b=7 and a=-1

OpenStudy (turingtest):

but the definition of f(x) is not the same throughout

OpenStudy (anonymous):

not f(x) F as in the anti-derivative lol

OpenStudy (turingtest):

I understand what you are saying, but hear me...

OpenStudy (anonymous):

Yeah so how do I deal with that lol?

OpenStudy (turingtest):

we have to treat this like two different integrands f(x) to begin with have you heard the word "integrand" before?

OpenStudy (anonymous):

no I haven't were in calc I

OpenStudy (anonymous):

rather I am in calc 1

OpenStudy (turingtest):

it's the function under the integral sign i.e. the function we area integrating is called the "integrand"

OpenStudy (turingtest):

we are*

OpenStudy (anonymous):

ahhh

OpenStudy (turingtest):

so at what value of x does the definition of the integrand f(x) change ?

OpenStudy (anonymous):

1

OpenStudy (anonymous):

correct?

OpenStudy (turingtest):

yes, very good! so we have two integrals, with two different integrands....

OpenStudy (turingtest):

from x=-1 to x=1 the integrand is what?

OpenStudy (anonymous):

x^2/2?

OpenStudy (anonymous):

rather x because the integrand is what we are doing to integrate right?

OpenStudy (turingtest):

in\[\int f(x)dx\]the integrand is just f(x) i.e. in \\[\int x^2dx\] the integrand is the function \(f(x)=x^2\)

OpenStudy (anonymous):

how did you get x^2?

OpenStudy (anonymous):

ohhhhh

OpenStudy (turingtest):

example only

OpenStudy (anonymous):

wow sorry half asleep

OpenStudy (anonymous):

lol

OpenStudy (anonymous):

yeah so its x!

OpenStudy (anonymous):

for -1 to 1

OpenStudy (turingtest):

yes

OpenStudy (anonymous):

so we have that now what? Integrate get x^2/2 then what?

OpenStudy (anonymous):

do -1^2/2 - 1^2/2?

OpenStudy (anonymous):

which is 0 lol

OpenStudy (turingtest):

you are right that the answer is zero, but it should be 1^2/2 - 1^2/2 the way you wrote it would result in -1

OpenStudy (turingtest):

so the first integral is zero... what is the second integral?

OpenStudy (anonymous):

1 to 7 the integral being ln |x|?

OpenStudy (anonymous):

muahahahaha! thats right! thanks!!!!!

OpenStudy (turingtest):

you are welcome :)

OpenStudy (turingtest):

thank you for being a good student

OpenStudy (anonymous):

^.^

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