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ITT: We go through the 3U paper and post up answers. (1 Viewer)

u-borat

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poWerdrY said:
thats what i thought, but then the equation of the parabola would be y= -ax(x-r). and i couldnt think of a way to get rid of a.
no, from x=vtcostheta and the y equivalent.

you make t the subject of the x equation, sub it into the y equation.

then you get y=xtantheta +blablabla something

and differentiate that, sub in x=Hcos@ and equate to tan wierd thing.
 

independantz

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poWerdrY said:
thats what i thought, but then the equation of the parabola would be y= -ax(x-r). and i couldnt think of a way to get rid of a.
since a parabola is symmetrical you can get the coords of L( r-w/2, h)you sub that it you get a and yo work it from there and you eventually get the answer, it was an algebra bash there might be an easier way but that's how i did it.
 

thewog2004

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eyy i got 12.45pm instead of 12.44pm...nearest min right or did i screw up?

n krap!...i got 27 instead of -27 for the first question LOL
 

poWerdrY

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thewog2004 said:
eyy i got 12.45pm instead of 12.44pm...nearest min right or did i screw up?

n krap!...i got 27 instead of -27 for the first question LOL
its 12:44. i almost put 12:45 as well, but i realised my answer was in decimals not degrees and minutes
 

scott.syd

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lovelle said:
i dont get 1)f) answer
domain for
loge ((x-3)(5-x))?
(x-3)(5-x) must always be positive, cause you can't log a negative number.
hence, u solve by inequalities:

x-3>0 or 5-x>0
x>3 or x<5
when u solve it, u should get
3<x<5
 

qqmore

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what did u guys get for amplitude and period for 5b)??

amplitude = 2/3 ???
 

independantz

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thewog2004 said:
eyy i got 12.45pm instead of 12.44pm...nearest min right or did i screw up?

n krap!...i got 27 instead of -27 for the first question LOL
same T_T for the 12:45 thing
oh well hopefully they aren't tight and just give us the mark :D
 

poWerdrY

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scott.syd said:
(x-3)(5-x) must always be positive, cause you can't log a negative number.
hence, u solve by inequalities:

x-3>0 or 5-x>0
x>3 or x<5
when u solve it, u should get
3<x<5

i cant beleive i fucking got that wrong. i looked at it as ln(x-3)(x-5). so i said x> 5. but i drew the graph. is there any chance that i might get 1 mark?
 

scott.syd

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poWerdrY said:
i cant beleive i fucking got that wrong. i looked at it as ln(x-3)(x-5). so i said x> 5. but i drew the graph. is there any chance that i might get 1 mark?
not too sure, maybe but prob not. if u did some logical working, u might get 1. so fingers crossed.
 

jess.!

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im pretty cut, i didnt put the time down as i misread the question and thought it was asking for how long it would take to cook in terms of minutes =[
ohhh.
do you think there is a chance of gettin 2/3 marks for that if i got the right answer but didnt add it to 9 am or 10 am or whatever it was?
 

henry08

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jess.! said:
im pretty cut, i didnt put the time down as i misread the question and thought it was asking for how long it would take to cook in terms of minutes =[
ohhh.
do you think there is a chance of gettin 2/3 marks for that if i got the right answer but didnt add it to 9 am or 10 am or whatever it was?
Of course. You'd certainly get 2, perhaps even 3.
 

poWerdrY

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jess.! said:
im pretty cut, i didnt put the time down as i misread the question and thought it was asking for how long it would take to cook in terms of minutes =[
ohhh.
do you think there is a chance of gettin 2/3 marks for that if i got the right answer but didnt add it to 9 am or 10 am or whatever it was?
definately 2/3
 

scott.syd

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independantz said:
i might be wrong but i got 0,pi/3,pi,5pi/3,2pi
how did u get pi/3 and 5pi/3. i got the quadratic with cos and then when
i factorised it i got (2cos+1)(cos-1), then cos=-1/2 so, the angle should be 2pi/3, 4pi/3 right? i dunno. maybe i stuffed up earlier.
 

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