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Mathematics 16 Online
OpenStudy (anonymous):

Integral help again

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

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?

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

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"

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!

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?

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?

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?

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

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

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

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?

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

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.

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

OpenStudy (anonymous):

thanks that is very generous of you.

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