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Q wrote on 2012-03-12 03:38
[Image: http://puu.sh/kpe8]
Can anyone help me do number 4? The answer is suppose to be 32pi/15. The equation I came up with was integral with bounds 0 - 2 (4-x^2)^2 dx times pi/2. I used my calculator to integrate it and it came out wrong. QQ.
EDIT: just noticed that the x axis is kinda cut off on number 4. It's all spaced 1 unit apart.
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Milk wrote on 2012-03-12 04:26
I think youtube vids would be able to help better than us
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Q wrote on 2012-03-12 04:30
but what will i search up. D: and the suggestion videos always end up side tracking me. :<
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Episkey wrote on 2012-03-12 04:34
What level of Math is this?
I mean, what Math class are you taking.
This doesn't look familiar, but it might be something I may have briefly forgotten.
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Q wrote on 2012-03-12 04:39
I'm currently in AP Calc AB. owo
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Episkey wrote on 2012-03-12 04:43
Quote from yoshii;804856:
I'm currently in AP Calc AB. owo
Sorry. That's out of my area of expertise >.<
I'm taking Calculus next semester.
But, best of luck! I'll be posting something very soon that might be helpful for you though.
You might want to try and see if that helps.
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Sayoko wrote on 2012-03-12 04:55
Uh wtf? Is this problem even solvable? There is no Z axis shown. I could find the area under the curve by intergrating each equation but thats about it. How do you find volume if you only have the equation y=4-x^2. You can intergrate that equation to 4x-X^3/3 to find the AUC. But how far does Z go? 2? Infinite?
Maybe if you can draw a picture explaining what "volume" i need to find, I can help you. I only see it in 2 dimensions right now with a random slice of the 2 dimensional equation. However, there is no insight on how far the slice goes due to a lack of Z axis or any information on it.
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Chihaya wrote on 2012-03-12 05:46
Quote from Sayoko;804875:
Uh wtf? Is this problem even solvable? There is no Z axis shown. I could find the area under the curve by intergrating each equation but thats about it. How do you find volume if you only have the equation y=4-x^2. You can intergrate that equation to 4x-X^3/3 to find the AUC. But how far does Z go? 2? Infinite?
Maybe if you can draw a picture explaining what "volume" i need to find, I can help you. I only see it in 2 dimensions right now with a random slice of the 2 dimensional equation. However, there is no insight on how far the slice goes due to a lack of Z axis or any information on it.
Basically this.
I've completed Calculus BC, and can tell you for sure that the problem is incomplete. From the looks of it, the problem looks like the rotation around a certain axis, (because of the perpendicular to x-axis part), but the fact that the "indicated area" is that little strip is bothering me; it's usually the area under the curve instead. It doesn't even say how wide that strip is, either
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Q wrote on 2012-03-12 06:53
I got the answer, but I guess our teacher hasn't included the z axis in solving it just yet. Apparently what I was suppose to do was set up integral with bounds 0 to 2, A(x) dx, where A(x) = area of the cross section. Because the cross section is a semi circle, A(x) = pi r^2/2. Then because that strip signifies the diameter of the semicircle, you divide the radius by 2. so in the end you get integral with bounds 0 - 2 pi (r/2)^2 / 2 dx. The radius is 4 - x^2 and so you just plug that in and integrate owo.