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#1 2017-08-04 01:08:39

Zeeshan 01
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Questions

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)


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#2 2017-08-04 01:37:01

zetafunc
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Re: Questions

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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#3 2017-08-04 02:06:38

Zeeshan 01
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Re: Questions

Q1 why with 120 not multiply x???


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#4 2017-08-04 02:07:46

Zeeshan 01
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Re: Questions

I set up exact eq but rs 120 prob


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#5 2017-08-04 02:07:54

zetafunc
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Re: Questions

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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#6 2017-08-04 02:09:16

Zeeshan 01
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Re: Questions

Question 4 cuts  at +-3 then integrated but ans not match


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#7 2017-08-04 02:13:37

zetafunc
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Re: Questions

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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#8 2017-08-04 02:15:01

Zeeshan 01
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Re: Questions

Yes ans is 36


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#9 2017-08-04 02:15:17

zetafunc
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Re: Questions

I agree with that result.

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#10 2017-08-04 02:16:12

Zeeshan 01
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Re: Questions

And question 2
f'(1)


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#11 2017-08-04 02:17:32

zetafunc
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Re: Questions

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

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#12 2017-08-04 02:17:56

Zeeshan 01
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Re: Questions

Which question


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#13 2017-08-04 02:20:51

zetafunc
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Re: Questions

Question 2.

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#14 2017-08-04 02:21:01

Zeeshan 01
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Re: Questions

Ok q2


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#15 2017-08-04 02:21:46

zetafunc
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Re: Questions

Are you able to find the slope of the normal?

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#16 2017-08-04 02:22:12

Zeeshan 01
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Re: Questions

Y=-1/7x+29/7

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


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#17 2017-08-04 02:24:08

zetafunc
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Re: Questions

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

Now, what is the slope of that line?

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#18 2017-08-04 02:56:08

Zeeshan 01
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Re: Questions

Slope is -1/7


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#19 2017-08-04 02:57:02

zetafunc
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Re: Questions

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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#20 2017-08-04 02:59:19

Zeeshan 01
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Re: Questions

A line that just touches a curve at one point, without cutting across it is called tangent


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#21 2017-08-04 03:00:18

zetafunc
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Re: Questions

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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#22 2017-08-04 03:01:37

Zeeshan 01
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Re: Questions

Can u draw


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#23 2017-08-04 03:02:52

zetafunc
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Re: Questions

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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#24 2017-08-04 03:04:26

Zeeshan 01
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Re: Questions

7


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#25 2017-08-04 03:05:02

zetafunc
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Re: Questions

That is correct.

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