Author Topic: maths C2 URGENT  (Read 2028 times)

Offline halosh92

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maths C2 URGENT
« on: February 21, 2010, 01:10:40 pm »
plz can anyone solve this!!!!!!!!!!!!!! my head broke!!!!!!!!!!!


the fixed point A has coordinates (8,-6,5) and the variable point P has coordiantes ( t, t , 2t)
a) show that AP^2= 6t^2 - 24t + 125
b) hence find the value of "t" for which the distance AP is least
c) determine this least distance
everyday we wake up is a miracle, then how do we say miracles dont happen?????

nid404

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Re: maths C2 URGENT
« Reply #1 on: February 21, 2010, 01:27:32 pm »
Can u tell which paper this is from...cuz something seems wrong...
the middle term in AP2 should be 12t and not -24t...
if i knw the paper i can cross check

Offline halosh92

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Re: maths C2 URGENT
« Reply #2 on: February 21, 2010, 01:30:38 pm »
Can u tell which paper this is from...cuz something seems wrong...
the middle term in AP2 should be 12t and not -24t...
if i knw the paper i can cross check

it is a pastpaper question but they put in our C2 skool textbook the year is not written but i think its pretty old.
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline astarmathsandphysics

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Re: maths C2 URGENT
« Reply #3 on: February 21, 2010, 02:20:42 pm »
Is f the question correct?

Offline halosh92

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Re: maths C2 URGENT
« Reply #4 on: February 21, 2010, 03:00:50 pm »
Is f the question correct?

i rili have no idea ???
everyday we wake up is a miracle, then how do we say miracles dont happen?????

nid404

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Re: maths C2 URGENT
« Reply #5 on: February 21, 2010, 03:40:16 pm »
ok...do u have ans at the back of your book?

If yes...then i can proceed my way and check if the other ans are right

Offline astarmathsandphysics

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Re: maths C2 URGENT
« Reply #6 on: February 21, 2010, 03:40:44 pm »
Should be home in 2 hours.

Offline Saladin

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Re: maths C2 URGENT
« Reply #7 on: February 21, 2010, 03:51:52 pm »
ppl, this question is a screwed one.

A point cannot have 3 co-ordinates. hehe

nid404

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Re: maths C2 URGENT
« Reply #8 on: February 21, 2010, 03:54:21 pm »
ppl, this question is a screwed one.

A point cannot have 3 co-ordinates. hehe

well spotted  :o

This is completely nuts :P

Offline halosh92

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Re: maths C2 URGENT
« Reply #9 on: February 21, 2010, 04:00:01 pm »
well spotted  :o

This is completely nuts :P

i totally agree ! i cant believe wat kind of people sit and make up such questions
yea i have the answers but there is nothing for the a) part :
b) t=2
c) square root 101 = 10.0
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline Phosu

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Re: maths C2 URGENT
« Reply #10 on: February 21, 2010, 04:45:12 pm »
oh yah i saw that question in the text book...didn't know how to solve so i skipped
but a point can have 3 coordinate, if you're considering the z axis, but then again we haven't been taught into such details
im sure its something simple, that we're just not getting it.

anyways i have one more question
could someone plz solve C2 question 8 Jun05,

nid404

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Re: maths C2 URGENT
« Reply #11 on: February 21, 2010, 04:52:58 pm »
assuming they are vectors A & P and using their first eqn...which i also think is wrong
U can solve the quadratic...
x=(-b +/- root of (b2-4ac))/ 2a
u get t as 2

AP2= 6(4)-24(2)+125=101
AP=root of 101= 10..

strange...



Offline astarmathsandphysics

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Re: maths C2 URGENT
« Reply #12 on: February 21, 2010, 04:54:57 pm »
the fixed point A has coordinates (8,-6,5) and the variable point P has coordiantes ( t, t , 2t)
a) show that AP^2= 6t^2 - 24t + 125
b) hence find the value of "t" for which the distance AP is least
c) determine this least distance
a)AP=sqrt((t-8)^2+(t--6)^2+(5-2t)^)
=sqrt(t^2-16t+64+t^2+12t+36+25-20t+4t^2)=sqrt(6t^2-24t+125)
b)AP^2=6t^2-24t+125
diffferentiate and put=0 and solve
12t-24=0 so t=2
c)AP^2 =6*2^2-24*2+125=24-48+125=101
least distance=sqrt(101)

Offline astarmathsandphysics

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Re: maths C2 URGENT
« Reply #13 on: February 21, 2010, 04:56:38 pm »
Which board is this? Not cie?

Offline halosh92

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Re: maths C2 URGENT
« Reply #14 on: February 21, 2010, 05:01:36 pm »
the fixed point A has coordinates (8,-6,5) and the variable point P has coordiantes ( t, t , 2t)
a) show that AP^2= 6t^2 - 24t + 125
b) hence find the value of "t" for which the distance AP is least
c) determine this least distance
a)AP=sqrt((t-8)^2+(t--6)^2+(5-2t)^)
=sqrt(t^2-16t+64+t^2+12t+36+25-20t+4t^2)=sqrt(6t^2-24t+125)
b)AP^2=6t^2-24t+125
diffferentiate and put=0 and solve
12t-24=0 so t=2
c)AP^2 =6*2^2-24*2+125=24-48+125=101
least distance=sqrt(101)

thanks alooot nid and astar  ;D ;D ;D
yea its is cie board!
everyday we wake up is a miracle, then how do we say miracles dont happen?????