Mathematics
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OpenStudy (megannicole51):
Find the integral of (x^6+4)^2 dx
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OpenStudy (anonymous):
square it!
OpenStudy (anonymous):
\[\int(x^{12}+8x^6+16)dx\]
OpenStudy (megannicole51):
so....(x^6+4)(x^6+4)? and use foil to calculate?
OpenStudy (anonymous):
square, yeah
OpenStudy (megannicole51):
hahah thats funny!
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OpenStudy (megannicole51):
so is that the answer? i feel like it can't be that simple!
OpenStudy (anonymous):
you made it to calculus right? time to drop "foil" from your vocab
and no, that is not the answer, that is how you are going to find the answer right?
OpenStudy (anonymous):
integrate term by term
OpenStudy (dan815):
the foil bomb
OpenStudy (anonymous):
\[\int x^{12}dx+8\int x^6dx+\int 16dx\]
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OpenStudy (megannicole51):
yeah im in calc 2 and at university....i like calling it foil.
OpenStudy (anonymous):
use the power rule backwards for each
\[\int x^ndx=\frac{x^{n+1}}{n+1}\]
OpenStudy (anonymous):
you good from there?
OpenStudy (dan815):
do they start integration in calc 2?
OpenStudy (megannicole51):
yeah they do
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OpenStudy (megannicole51):
my professor doesnt speak very good english so I'm trying to learn the material and try to understand what hes saying lol
OpenStudy (megannicole51):
and what do u mean the power rule backwards?
OpenStudy (dan815):
watch youtube videos on it there are a lot
OpenStudy (dan815):
derivative backwards
OpenStudy (dan815):
just think what do i need to take the derivative of to get that
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OpenStudy (dan815):
like 16...
d/dx of 16x = 16
OpenStudy (dan815):
d/dx of 16x+c is also=16
OpenStudy (megannicole51):
ooooh i get it but how would u do like x^10?
OpenStudy (dan815):
for x^6
....
d/dx of 1/7*x^7 = x^6
OpenStudy (megannicole51):
so it would be x^9?
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OpenStudy (anonymous):
\[\int x^{10}dx=\frac{x^{11}}{11}\] etc
OpenStudy (dan815):
d/dx 1/11 * x^11=x^10
OpenStudy (anonymous):
add one to the exponent, then divide by that number
OpenStudy (dan815):
u addin +1 to exponent and dividing by thaat exponent
OpenStudy (dan815):
the inverse of derivative power formula
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OpenStudy (anonymous):
this is what i means by the power rule backwards
\[\int x^ndx=\frac{x^{n+1}}{n+1}\] since the power rule is
\[\frac{d}{dx}[x^n]=nx^{n-1}\]
OpenStudy (dan815):
for derivavtive u multiple my exp then subtract -1 from exp
so backwards is
+1 to exp and divide by exp
OpenStudy (dan815):
u multiply*
OpenStudy (anonymous):
power rule
multiply by the exponent, drop the power by 1
power rule backwards
add one to the exponent, divide by it
OpenStudy (dan815):
loser!! buddy
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OpenStudy (dan815):
hows java coming along
OpenStudy (megannicole51):
so if i had the integral of (x^12 dx+8) that would just be x^11?
OpenStudy (dan815):
no
OpenStudy (megannicole51):
okay im confused im sorry
OpenStudy (dan815):
ok ill make it simple
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OpenStudy (dan815):
derivative of x^2 =?
OpenStudy (megannicole51):
2x
OpenStudy (dan815):
integral of 2x =?
OpenStudy (megannicole51):
2?
OpenStudy (dan815):
no its x^2
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OpenStudy (megannicole51):
okay
OpenStudy (dan815):
try this
OpenStudy (megannicole51):
okay:)
OpenStudy (dan815):
3x^2
OpenStudy (dan815):
integral of that?
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OpenStudy (dan815):
its gonna be confusing for the first week u will mix up derivatives and integrals, we all did, but u will get used to it
OpenStudy (megannicole51):
okay i dont understand how you are taking the integral simple equations....i dont remember how to do them
OpenStudy (megannicole51):
thanks for the reassurance :)
OpenStudy (dan815):
okAY look carefully what we are doing for derivative
OpenStudy (megannicole51):
yes i can take the derivative
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OpenStudy (dan815):
d/dx of x^3 =
OpenStudy (megannicole51):
3x^2
OpenStudy (megannicole51):
so the integral is x^3?
OpenStudy (anonymous):
\[\int xdx=\frac{x^2}{2}\\\int x^2dx=\frac{x^3}{3}\\\int x^3dx=\frac{x^4}{4}\\\int x^4dx=\frac{x^5}{5}\\\int x^ndx=\frac{x^{n+1}}{n+1}\]
OpenStudy (dan815):
yeah
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OpenStudy (dan815):
break up the steps though, so for derivative u first multipled by the exponent and subtracted 1 from the exponent
OpenStudy (megannicole51):
so x^12 is x^13/13?
OpenStudy (dan815):
yes
OpenStudy (megannicole51):
ooooh okay
OpenStudy (megannicole51):
so what do u do if u just have say 5?
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OpenStudy (dan815):
5x
OpenStudy (dan815):
theres a catch to all this though, there can be a constant there too
OpenStudy (dan815):
for example d/dx 5x+1 = 5
so is d/dx 5X +2 = 5
d/dx 5x+c = 5
OpenStudy (dan815):
so just keep doing whatever u are doing, but after u get ur integral answer just add a c to it
OpenStudy (megannicole51):
okay so for the actual problem it would be the integral of x^13/13+8x integral x^7/7 dx + integral 16x dx?
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OpenStudy (megannicole51):
sorry i dont know how to make my equations look fancy lol
OpenStudy (dan815):
the integral and dx sighs are lost once u do the integration buy yes
OpenStudy (megannicole51):
so is that the answer to the problem? or is there more?
OpenStudy (dan815):
x^13/13+8x +x^7/7 +16x +c
OpenStudy (dan815):
that sthe answer
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OpenStudy (dan815):
u can simplify it but ya
OpenStudy (megannicole51):
why is it set up like that? do u know?
OpenStudy (dan815):
like what
OpenStudy (megannicole51):
why do they take out the integrals?
OpenStudy (dan815):
its just an operator sign like d/dx
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OpenStudy (dan815):
after u do d/dx of 5x
OpenStudy (dan815):
u will get 5 not d/dx of 5 right
OpenStudy (megannicole51):
my online thing says its wrong:(
OpenStudy (dan815):
samething with integral and dx
d/dx mEANS DERIVATIVE WITH RESPECT TO X
integral dx means integral with respect to x
OpenStudy (megannicole51):
so like change the 8x to 8? and 16x to 16?
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OpenStudy (dan815):
what do u mean
OpenStudy (megannicole51):
the answer was wrong is there something we are missing?
OpenStudy (dan815):
did u add the c
OpenStudy (megannicole51):
yes
OpenStudy (dan815):
try without it then
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OpenStudy (megannicole51):
nope didnt work
OpenStudy (dan815):
what are u entering
OpenStudy (megannicole51):
x^13/13+8x+x^7/7+16x+c
OpenStudy (dan815):
its 8x^7/7
OpenStudy (dan815):
why dont u add the 8x and 16x together too
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OpenStudy (megannicole51):
then is it 16x^15/15?
OpenStudy (dan815):
wuuttt lool