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September 10, 2025, 08:27:07 am

Author Topic: Mathematics Question Thread  (Read 1626460 times)  Share 

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Re: Mathematics Question Thread
« Reply #2175 on: July 15, 2017, 07:25:46 pm »
+1

WolframAlpha input
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You could've used integration for both if you wanted to. Their method is also acceptable.

So just to clarify the procedure for 1 (non 3U algebra method):

  • Interpret from the information given that the region occurs when y >= 1 for the original equation
  • Express the original equation in terms of x to find x <= 3
  • Test a point on either side of the asymptote (x=2) with the original equation considering what's been obtained
  • Shade the region

For 2 I tried integration initially but got the wrong answer. Don't think we covered volumes generated by an area between two intersecting functions. Are any of these on the right track? Should I be trying to split up the volumes and subtracting/adding them with separate integrations or does it work like the area between two intersecting functions?



RuiAce

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Re: Mathematics Question Thread
« Reply #2176 on: July 15, 2017, 07:40:37 pm »
+1
So just to clarify the procedure for 1 (non 3U algebra method):

  • Interpret from the information given that the region occurs when y >= 1 for the original equation
  • Express the original equation in terms of x to find x <= 3
  • Test a point on either side of the asymptote (x=2) with the original equation considering what's been obtained
  • Shade the region

For 2 I tried integration initially but got the wrong answer. Don't think we covered volumes generated by an area between two intersecting functions. Are any of these on the right track? Should I be trying to split up the volumes and subtracting/adding them with separate integrations or does it work like the area between two intersecting functions?

(Image removed from quote.)

Testing is up to you and perfectly safe. I prefer using my intuition or doing it in my head but there's nothing wrong with testing if you know what you're doing.
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If you were rotating about the x-axis, you'd have a volume between two curves similar to the first one.

But you're rotating about the y-axis. If you treated this is an area question, you would have a compound region and be adding the area integrals. Hence, you should be adding the volume integrals here as in equation 3.

jaskirat

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Re: Mathematics Question Thread
« Reply #2177 on: July 15, 2017, 08:05:38 pm »
0
Hey guys can you help me with this question, cheers!

junzhang

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Re: Mathematics Question Thread
« Reply #2178 on: July 15, 2017, 09:29:56 pm »
0
Hey,
Could you help me with this question?
I'm not sure how to find the focal length and I can't get the required proof. Thank you!

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Re: Mathematics Question Thread
« Reply #2179 on: July 15, 2017, 09:44:21 pm »
0
Testing is up to you and perfectly safe. I prefer using my intuition or doing it in my head but there's nothing wrong with testing if you know what you're doing.
________________________

If you were rotating about the x-axis, you'd have a volume between two curves similar to the first one.

But you're rotating about the y-axis. If you treated this is an area question, you would have a compound region and be adding the area integrals. Hence, you should be adding the volume integrals here as in equation 3.

Thanks a bunch m8

kiwiberry

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Re: Mathematics Question Thread
« Reply #2180 on: July 15, 2017, 09:47:24 pm »
+1
Hey,
Could you help me with this question?
I'm not sure how to find the focal length and I can't get the required proof. Thank you!

Hello!
h=40 and k=0 because the vertex is at (40,0). Because A(30,50) lies on the curve, we can sub it into the equation to find the focal length
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hansolo9

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Re: Mathematics Question Thread
« Reply #2181 on: July 15, 2017, 10:33:51 pm »
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Hello, can I have help with the attached question?
I haven't seen these types of radian questions yet

RuiAce

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Re: Mathematics Question Thread
« Reply #2182 on: July 15, 2017, 11:00:01 pm »
+1

Hello, can I have help with the attached question?
I haven't seen these types of radian questions yet

hansolo9

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Re: Mathematics Question Thread
« Reply #2183 on: July 15, 2017, 11:11:25 pm »
+1

Omg how did i not see that...
Thanks Rui :)

sophiegmaher

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Re: Mathematics Question Thread
« Reply #2184 on: July 16, 2017, 11:51:08 am »
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So I'm really confused as to how the x-intercept of the function y=6ln(x-1) is (2,0)? I understand you let the equation equal to 0, but I don't get how that will equal to 2?
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ellipse

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Re: Mathematics Question Thread
« Reply #2185 on: July 16, 2017, 11:57:06 am »
+1
So I'm really confused as to how the x-intercept of the function y=6ln(x-1) is (2,0)? I understand you let the equation equal to 0, but I don't get how that will equal to 2?

0=6ln(x-1)
ln(x-1)=0
x-1=e^0
x-1=1
x=2
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mx2-99
mx1-98
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chem-94
eng-88 (rip me)

sophiegmaher

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Re: Mathematics Question Thread
« Reply #2186 on: July 16, 2017, 12:00:21 pm »
0
0=6ln(x-1)
ln(x-1)=0
x-1=e^0
x-1=1
x=2

Thank you!!
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Kekemato_BAP

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Re: Mathematics Question Thread
« Reply #2187 on: July 16, 2017, 07:41:12 pm »
0
Hi, may I have help on question 14b?
Thanks :)
Hello

RuiAce

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Re: Mathematics Question Thread
« Reply #2188 on: July 16, 2017, 07:58:11 pm »
+2
Hi, may I have help on question 14b?
Thanks :)
Important warning: The Extension questions in Cambridge are designed purely for the sake of self-interest. They are only for you to build superior techniques when you feel necessary. In general, I will not do questions from this section, as they very often go well beyond the scope of the course in question.

« Last Edit: July 16, 2017, 08:29:49 pm by RuiAce »

itssona

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Re: Mathematics Question Thread
« Reply #2189 on: July 17, 2017, 06:28:31 pm »
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This is rlly dumb but.. how would you exactly know cot (-135)

Do we see tan? And how do we use our knowledge of quadrants

Thank you
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