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**Zeeshan 01****Member**- Registered: 2016-07-22
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Q1. Three brothers divide X rupees such that the elder gets 2/5 of it, middle gets 1/3 of it and younger gets rs 120.What was X

options(1800,450,1200,none of these)

Q2. If equation of line normal to any curve f(x) at (1,4) isx+7y=29, then f'(1) is

options(7,1,1/7,4)

Q3. Let A,B,C are points on line and B is between A and C.Let M and N are Midpoints of AB and BC.If AB;BC=3:1, What is MN:BC???

Options(1:3,1:2,2:3,2:1)

Q4. Area bounded By curve y=9-(x)^2 and x axis is

Options(1/3,2,ln2,ln(3)/2)

*Last edited by Zeeshan 01 (2017-08-04 03:13:05)*

MZk

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For Q1, you'll want to set up the equation (do you see why?).

For Q2, could you double-check what the exact wording of the question is? (I'm not sure what "derivative of f(1)" means here.) As a guess, I suspect that you want the slope of the tangent line at x = 1. If so, you should use the fact that the product of the slopes of the normal and tangent line are -1.

For Q3, try drawing a line on some paper and plot A, B, C (in that order). Then plot the midpoints M, N, and assume for simplicity that BC has length 1. Can you determine the lengths of MB and BN, and therefore deduce the ratio MN:BC?

For Q4, first work out where this function cuts the x-axis (it does so in two places -- don't forget that it's symmetric about the y-axis). Integrating will then give you the answer.

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Q1 why with 120 not multiply x???

MZk

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**Zeeshan 01****Member**- Registered: 2016-07-22
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I set up exact eq but rs 120 prob

MZk

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Because the question says that we want to share out of the original number, and of the original number. The 120 rs is not a proportion of anything, it is just a number.

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Question 4 cuts at +-3 then integrated but ans not match

MZk

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I'm getting 36 for the area -- so it seems that, as you point out, the answers do not match. Did you copy the question/options correctly?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Yes ans is 36

MZk

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I agree with that result.

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**Zeeshan 01****Member**- Registered: 2016-07-22
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And question 2

f'(1)

MZk

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Can you rewrite the equation of the normal in the form ?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Which question

MZk

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Question 2.

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Ok q2

MZk

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Are you able to find the slope of the normal?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Y=-1/7x+29/7

*Last edited by Zeeshan 01 (2017-08-04 02:55:30)*

MZk

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Correct, but the last term should say 29/7.

Now, what is the slope of that line?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Slope is -1/7

MZk

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Correct. So the slope of the normal is -1/7.

Using this, what is the slope of the tangent line at that point?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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A line that just touches a curve at one point, without cutting across it is called tangent

MZk

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Yes, and can you use the fact that the slope of the normal is -1/7 to find the slope of the tangent line?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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Can u draw

MZk

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There is no need to draw anything. The tangent line and the normal line are perpendicular, and their slopes multiply to give -1. If the slope of the normal is -1/7, can you find the slope of the tangent line?

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**Zeeshan 01****Member**- Registered: 2016-07-22
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7

MZk

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That is correct.

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