fjans5 Posted May 5, 2015 Report Share Posted May 5, 2015 Hi! I'm having trouble with an integration problem. 2π × integral between 0 and 6 of (0.02x^3-0.39x^2+1.77x+0.18) × (sqrt(0.0036x^4-0.0936x^3+0.8208x^2-2.7612x+4.1329)) dx Does anyone know how to solve it or have any suggestions? Thanks heaps! Reply Link to post Share on other sites More sharing options...
Vioh Posted May 5, 2015 Report Share Posted May 5, 2015 (edited) Hi! I'm having trouble with an integration problem. 2π × integral between 0 and 6 of (0.02x^3-0.39x^2+1.77x+0.18) × (sqrt(0.0036x^4-0.0936x^3+0.8208x^2-2.7612x+4.1329)) dx Does anyone know how to solve it or have any suggestions? Thanks heaps! The numbers in this integral seem to be very irregular, so I don't think you have to solve this by hand. Using my Ti-84, the answer is: 82.6Here are the workings: , , Hope this helps Edited May 5, 2015 by Vioh 1 Reply Link to post Share on other sites More sharing options...
fjans5 Posted May 5, 2015 Author Report Share Posted May 5, 2015 Hi! I'm having trouble with an integration problem. 2π × integral between 0 and 6 of (0.02x^3-0.39x^2+1.77x+0.18) × (sqrt(0.0036x^4-0.0936x^3+0.8208x^2-2.7612x+4.1329)) dx Does anyone know how to solve it or have any suggestions? Thanks heaps! The numbers in this integral seem to be very irregular, so I don't think you have to solve this by hand. Using my Ti-84, the answer is: 82.6Here are the workings: a1.png, a2.png, a3.png Hope this helps This helps thanks! But I also need to show the working for this problem. Would you know how to do this? Thank you so much! Reply Link to post Share on other sites More sharing options...
Vioh Posted May 5, 2015 Report Share Posted May 5, 2015 This helps thanks! But I also need to show the working for this problem. Would you know how to do this? If this is part of your IA or something similar, then the photographs of the calculator themselves can be used to show the working for the problem. On the other hand, if this problem is in the IB exam for example, then you don't really need to show any workings at all. It is enough to just say: Using the GDC (graphic display calculator), the answer to this integral is 82.6 1 Reply Link to post Share on other sites More sharing options...
fjans5 Posted May 5, 2015 Author Report Share Posted May 5, 2015 This helps thanks! But I also need to show the working for this problem. Would you know how to do this? If this is part of your IA or something similar, then the photographs of the calculator themselves can be used to show the working for the problem. On the other hand, if this problem is in the IB exam for example, then you don't really need to show any workings at all. It is enough to just say: Using the GDC (graphic display calculator), the answer to this integral is 82.6 Ok thank you for all your help Reply Link to post Share on other sites More sharing options...
Slovakov Posted May 5, 2015 Report Share Posted May 5, 2015 (edited) I'll cast a shade of doubt... when I copied the integral to Wolfram Alpha, it showed the result as 13.1478http://www.wolframalpha.com/input/?i=integrate+%280.02x%5E3-0.39x%5E2%2B1.77x%2B0.18%29*%28sqrt%280.0036x%5E4-0.0936x%5E3%2B0.8208x%5E2-2.7612x%2B4.1329%29%29+dx+from+x%3D0+to+6 Edit: my bad, forgot to multiply it by 2*pi, it is 82.61 in the end. Edited May 5, 2015 by Slovakov 2 Reply Link to post Share on other sites More sharing options...
Vioh Posted May 5, 2015 Report Share Posted May 5, 2015 I'll cast a shade of doubt... when I copied the integral to Wolfram Alpha, it showed the result as 13.1478http://www.wolframalpha.com/input/?i=integrate+%280.02x%5E3-0.39x%5E2%2B1.77x%2B0.18%29*%28sqrt%280.0036x%5E4-0.0936x%5E3%2B0.8208x%5E2-2.7612x%2B4.1329%29%29+dx+from+x%3D0+to+6 oh, I think that's because you forgot to put the 2pi in front of it. Notice that 2pi * 13.1478 = 82.6 2 Reply Link to post Share on other sites More sharing options...
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