Mathematics
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OpenStudy (anonymous):
Integral help again
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OpenStudy (anonymous):
can someone solve any problem from no 12?
OpenStudy (anonymous):
and 12 at the end also?
OpenStudy (anonymous):
\[f(1)=0\]
OpenStudy (anonymous):
\[\int_1^1 f(t)dt = 0\]
OpenStudy (anonymous):
\[f'(x)=\sqrt{1+2x}\]because the derivative of the integral is the integrand
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OpenStudy (anonymous):
\[f'(4)=\sqrt{9}=3\]
OpenStudy (anonymous):
cause that is what you get when you replace x by 4
OpenStudy (anonymous):
is the last one
\[f'(x^2)\]?
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
in C how di you replace t?
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OpenStudy (anonymous):
ok \[f(x)=\int_1^x f(t)dt\] so \[f(x^2)=\int_1^{x^2} f(t)dt\]
OpenStudy (anonymous):
in C?
\[f'(x)=\sqrt{1+2x}\] yes?
OpenStudy (anonymous):
so you replace t with the x value right? I got it
OpenStudy (anonymous):
exactly
OpenStudy (anonymous):
k last one
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OpenStudy (anonymous):
\[f(x)^2=\int_1^{x^2}\sqrt{1+2t}dt\]
OpenStudy (anonymous):
that should have been \[f(x^2)\]
myininaya (myininaya):
OpenStudy (anonymous):
now you take the derivative using the chain rule
OpenStudy (anonymous):
derivative of "outside function" evaluated at "inside function" times derivative of "inside function"
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OpenStudy (anonymous):
here "outside" is the integral, "inside" is x^2
OpenStudy (anonymous):
\[\frac{d}{dx}\int_1^{x^2} \sqrt{1+2t} dt=\sqrt{1+2x^2} \times 2x\]\]
OpenStudy (anonymous):
i replaces t by x^2 and then multiplied at the end
OpenStudy (anonymous):
got it.
OpenStudy (anonymous):
good!
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OpenStudy (anonymous):
Well, I did 10 by myself but can you check my answer A=6, B=-2.5 C=.5
OpenStudy (anonymous):
hello myininaya!
myininaya (myininaya):
someone said they could not open my file earlier
can someone give it a try to see if it still doesn't open?
hey satellitle
OpenStudy (anonymous):
which file?
OpenStudy (anonymous):
cheater. where is the latex?
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OpenStudy (anonymous):
i will try but i can barely read them
myininaya (myininaya):
ravsau scroll up the file should be there
OpenStudy (anonymous):
A it's 0 to 3 B; 2 to 5 C; 7 to 3
OpenStudy (anonymous):
ok the idea is you take the anti derivative, put the +C replace x by 2 and set the result = 1 to solve for C
OpenStudy (anonymous):
dont you just count the triangles? because integrals = area? something like that?
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OpenStudy (anonymous):
first is \[\frac{-1}{x}+\frac{x^2}{2}+C\]
OpenStudy (anonymous):
#10?
myininaya (myininaya):
i think he is talking about the second 10
OpenStudy (anonymous):
hey myininaya i could open your file . Thanks for your effort
OpenStudy (anonymous):
the second ten?
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OpenStudy (anonymous):
second 10 yes.graphing one
myininaya (myininaya):
yes just use areas to find the areas or net areas under the curve
myininaya (myininaya):
areas of triangles*
OpenStudy (anonymous):
mininaya can you do it? i am old and tired and my eyes hurt
myininaya (myininaya):
this is some really bad lag for me
i don't know how much longer i can stay and let this lag lag me
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OpenStudy (anonymous):
plus i need to go get my beauty rest
myininaya (myininaya):
satellite wants to do it
i don't want to take his thunder
OpenStudy (anonymous):
actually this is all jumping around. area of rectangle and triangles. i guess i can try it
OpenStudy (anonymous):
cool
OpenStudy (anonymous):
i get 6.5 for the first one
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OpenStudy (anonymous):
from 2 to 5 looks like 0
myininaya (myininaya):
(1)1+3*1*1/2+4*2*1/2=1+3/2+4=5+3/2+13/2
gj on the first one
OpenStudy (anonymous):
yes especially since i eyeballed it
OpenStudy (anonymous):
how bout the second?
myininaya (myininaya):
those two triangles have the same area except one is above the x-axis and one is below so the net area is 0
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OpenStudy (anonymous):
i get 1/2 for the last one
myininaya (myininaya):
7 to 3?
or
3 to 7?
myininaya (myininaya):
ok 7 to 3
OpenStudy (anonymous):
last one 7 to 3
OpenStudy (anonymous):
so A was 6.5? B was 0 c half?
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myininaya (myininaya):
yes i get the same
if we look from 3 to 7 we have
-1/2*1*2+(-1/2*1*1)+1/2*2*1=-1/2
so from 7 to 3 we have 1/2
gj satellite
OpenStudy (anonymous):
that is what i got. but my eyes are off tonight and this thing is jumping around like crazy. i will wait for my learned colleague to reply
OpenStudy (anonymous):
amistre made it to 1000 today!
OpenStudy (anonymous):
i was so chuffed with myself for giving him his 1000 th medal
myininaya (myininaya):
he said he will let me have his bike and not you
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OpenStudy (anonymous):
can i ring the bell at least?
myininaya (myininaya):
no!
OpenStudy (anonymous):
find my post and condulate him
OpenStudy (anonymous):
:(
OpenStudy (anonymous):
k thanks guys.
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OpenStudy (anonymous):
gnight all
myininaya (myininaya):
lol
its for you own good
if you ring the bell you will get too attached
later ravsau
OpenStudy (anonymous):
grrrr
myininaya (myininaya):
nite satellite
you can ring the bell once
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OpenStudy (anonymous):
thanks that is very generous of you.