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Just tabulate the data in your calculator. There will be an option for probability stuff. Which TI do you have? Would be best to ask somebody who has the same type of calculator.

Ti-84 ! the problem is that I dont know what values I need to input the upper values or the down values from the table ?

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Do I have to wait til July to know what my IA grade was in Math Studies?

Yes. As far as I know we get our final point grades on the 6th and a few days later our exact grades for each section (IAs, papers, etc)... Not sure if that's true, but I recall the teacher mentioning that. However, your teacher probably told you what he gave you? This might be moderated, but it's usually about 2 points or so, nothing drastic...

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  • 3 weeks later...

using | for integral sign

|(ex)/(e2x+9)dx

Let u=ex therefore du=exdx so dx=1/ex

Plug stuff in and you get |1/(u2+9)

Quickly notice that it's ALMOST arctan and actually is a form of it. You just need to get that 9 out of there somehow.

Now it might just be too early for me but I checked my answer with Wolframalpha and got something different but I don't know what they are doing.

Factor that nine out of the bottom so you have (1/9)|1/(u/9)2+1

That gives you an answer of (1/9)arctan(u/9) or (1/9)arctan(ex/9)

Wolfram alpha got (1/3)arctan(u/3) which didn't seem right, take the derivative and I didn't get the integrant you posted >.<

*Derivative of (1/3)arctan(u/3) is 1/(u2/3)+3 isn't it? O.o

Yep, too early for me to do calc at the time, refer to post under me...

Edited by Drake Glau
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  • 2 weeks later...

using | for integral sign

|(ex)/(e2x+9)dx

Let u=ex therefore du=exdx so dx=1/ex

Plug stuff in and you get |1/(u2+9)

Quickly notice that it's ALMOST arctan and actually is a form of it. You just need to get that 9 out of there somehow.

Now it might just be too early for me but I checked my answer with Wolframalpha and got something different but I don't know what they are doing.

Factor that nine out of the bottom so you have (1/9)|1/(u/9)2+1

That gives you an answer of (1/9)arctan(u/9) or (1/9)arctan(ex/9)

Wolfram alpha got (1/3)arctan(u/3) which didn't seem right, take the derivative and I didn't get the integrant you posted >.<

*Derivative of (1/3)arctan(u/3) is 1/(u2/3)+3 isn't it? O.o

You're close, but if you differentiate (1/3)arctan(u/3) you get (1/3) * 1/((u/3)^2 + 1) * (1/3) = 1/(u^2 + 9) - use the chain rule.

If you'd like to know where arctan comes from in the integration, you need to substitute u/3 = tan(theta). Can't be bothered to write it out in text, so I've done it on Word and screenshotted:

2mrt9j5.gif

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Need help with this:

The cost C of ordering and storing x unites of a product is C(x) = x + (10000/x). A delivery truck can deliver at most 200 units per order. Find the order size that will minimize the cost.

Thank you! I think you have to use the first and the second derivative....

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