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Mathematics: Post your doubts here!

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depends on u... i loved p3 as compared to s1.
ii gave accelerated... and u wont guess.... with s2
got a b :/
and that also after only two months study of s2 :(
 
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ok here goes to find the limits of this curve y= sin cube 2x cos cube 2x we will put y=0 as on the x axis y=o
0= cos cube2x sin cube 2x o=sin cube 2x
sin cube 2x = 0 0 = cos cube 2x
x=0 2x=pi/2

x= pi/4

so the limits be pi/4 and 0

by substituting u= sin2x
du/dx = 2cos2x
du= 2cos2x dx

now substituting

(cos cube 2x)( u^3) (1/ 2cos2x) <----------- where this is du
one cos would be cut by the cos in the denominator
u^3 (cos square 2x)/2
remember that cos square x = 1-sin square x
so cos square x = 1-sin square x
so
cos square 2x = 1-sin square 2x
and sin 2x =u
so
cos square 2x= 1- u^2
then the total thing wud be
1/2 integral of u^3(1-u^2)
1/2 integral of u^3 - u^5
1/2 (( u^4)/4 - (u^6)/6)
now open u as sin2x
1/2 (( sin 2x^4)/4 - (sin 2x^6)/6)
1/2 (1/4- 1/6)
1/2 (1/12)
1/24
 
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here are two hints that id give and i want you to do it urself
a) use the M1*M2 =-1 use this to take out the gradient of BD take midpoint
u have a grad u have coordinates make eq of line of BD
then to find b put x=0 as it is on the y axis



thenu have coords of B and M the midpoint
u can say that (coords of b + coords of c )/2 willgive you the coords of M the midpoint
here u can put midpoint and B to get the coords of C :)
 
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5173b8b83b42a.png


I managed to get both M and A... but not C. Could anyone explain how to obtain the answer for C?

I'm reposting my query because it seems no one saw it and it got buried two pages back LOL.
 
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here are two hints that id give and i want you to do it urself
a) use the M1*M2 =-1 use this to take out the gradient of BD take midpoint
u have a grad u have coordinates make eq of line of BD
then to find b put x=0 as it is on the y axis



thenu have coords of B and M the midpoint
u can say that (coords of b + coords of c )/2 willgive you the coords of M the midpoint
here u can put midpoint and B to get the coords of C :)
thanks ... just by readind ur first sentence i remembered the concept
i think ur a magician ;)
 
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I'm reposting my query because it seems no one saw it and it got buried two pages back LOL.
Okay once you have the co ordinates of A and M, you have done the toughest part.
Since you havent given the co ordinates of A and M, im gonna take the numbers that come firrst in my head, A and M in this situation be (4,0) and (2,4)
Okay now Let C be (p,q)
Now we use Mid point formulas.
(4+p/2 = 2), (0+q = 4)
Find p and q.
we used the mid point formulas because M is the mid point of A and C. We have the points of A and M. Fill in the missing spaces.
yet again mid point = (x1+x2/2 , y1+y2/2) Use the co ordinates of A(and let C be p,q), which equals to co ordinates of M. Hope it helps!
 
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I'm reposting this.. anyone?


Q7 i) Atleast one 3 .. means that it is saying P(X≥1) or P(X>0) n = 9

Where X is the number of 3s.

So for it to be zero 3s the probability will be (5/6) and 0 3s at all 9 throws would be P(X=0)=(5/6)^9

Now it asked at least 1 3 .. meaning there are no zeros .. so 1 - P(X=0) = 1- (5/6)^9 = 0.806 Answer

ii) When n fair dice are thrown, the probability of getting at least one 3 is greater than 0.9.
Find the smallest possible value of n.

This is a real tricky question .. we know that for one dice which is thrown 9 times the probability of getting atleast one 3 is 1-(5/6)^9

so for n number of throws the probability will be 1- (5/6)^n

Now the question says .. the probability of n number of throws is 0.9 so

0.9 = 1-(5/6)^n
-0.1=-(5/6)^n
(5/6)^n=0.1

Now To get the value of n we need to use ln on both sides (a little something from my add maths).. using ln would get the power to the bottom

n* ln (5/6)= ln(0.1)
n = ln (0.1) / ln(5/6)
n = 12.62

so atleast 13 throws need to be made for the probability to be 0.9.

b)

This was a real tricky question .. I remember my friend asked me solve it..

5 Green Balls 3 Yellow Balls .. Player wins when a yellow ball is drawn.. Julie draws the first ball .. Probability of Ronnie Winning..

The ways in which ronnie can win are as follows

J'R , J'R'J'R , J'R'J'R'J'R (then the green balls end so yellow ball would come eventually..) To summarize these details in terms of balls
GY , GGGY, GGGGGY

Total = 9, 5 green and 3 yellow.. so probabilities become

P(GY) = (5/8 * 3/7) = 15/56

P(GGGY) = (5/8 * 4/7 * 3/6 * 3/5) = 3/28

P(GGGGGY) = (5/8 * 4/7 * 3/6 * 2/5 * 1/4 * 3/3) = 1 / 56

Total P = 15/56 + 3/28 + 1/56 = 11/28 Answer


Hope that helps...
 
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Q7 i) Atleast one 3 .. means that it is saying P(X≥1) or P(X>0) n = 9

Where X is the number of 3s.

So for it to be zero 3s the probability will be (5/6) and 0 3s at all 9 throws would be P(X=0)=(5/6)^9

Now it asked at least 1 3 .. meaning there are no zeros .. so 1 - P(X=0) = 1- (5/6)^9 = 0.806 Answer

ii) When n fair dice are thrown, the probability of getting at least one 3 is greater than 0.9.
Find the smallest possible value of n.

This is a real tricky question .. we know that for one dice which is thrown 9 times the probability of getting atleast one 3 is 1-(5/6)^9

so for n number of throws the probability will be 1- (5/6)^n

Now the question says .. the probability of n number of throws is 0.9 so

0.9 = 1-(5/6)^n
-0.1=-(5/6)^n
(5/6)^n=0.1

Now To get the value of n we need to use ln on both sides (a little something from my add maths).. using ln would get the power to the bottom

n* ln (5/6)= ln(0.1)
n = ln (0.1) / ln(5/6)
n = 12.62

so atleast 13 throws need to be made for the probability to be 13.

b)

This was a real tricky question .. I remember my friend asked me solve it..

5 Green Balls 3 Yellow Balls .. Player wins when a yellow ball is drawn.. Julie draws the first ball .. Probability of Ronnie Winning..

The ways in which ronnie can win are as follows

J'R , J'R'J'R , J'R'J'R'J'R (then the green balls end so yellow ball would come eventually..) To summarize these details in terms of balls
GY , GGGY, GGGGGY

Total = 9, 5 green and 3 yellow.. so probabilities become

P(GY) = (5/8 * 3/7) = 15/56

P(GGGY) = (5/8 * 4/7 * 3/6 * 3/5) = 3/28

P(GGGGGY) = (5/8 * 4/7 * 3/6 * 2/5 * 1/4 * 3/3) = 1 / 56

Total P = 15/56 + 3/28 + 1/56 = 11/28 Answer


Hope that helps...
wow such long answers :p
 
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