Ext-1 CSSA 04 (1 Viewer)

[withoutaface]

aww!! can someone post up the cssa 04

We don't get it back for ages.

 

[Crikket]

i thought it was so much harder than the 4 unit exam, at least i got to write one "QED" after a question in the extension 2 paper... the extension 1 paper was hard!

 

[govich]

IMO very easy, walked out thinking "i love 3 unit maths!" after yesterday

had a mental blank, couldn't understand the surface area of the circle question, decide to take a 5 minute break and then start working again, all good

I counted marks i may/may not have lost where i was slightly unsure and i have about 5-6 marks off max.

what did everyone get for the volume question?

 

[withoutaface]

Throw some numbers at me and I'll be able to tell you if thats what I got.

 

[za]

for the induction question
c how u get:
5.5^k > 4.4^k + 3.3^k

can u divide it all by 5. ending with:

5^K > (0.8)4^k + (0.6)3^k

then u can say, seeing as though 5^k > 4^k + 3^k, then it is obviuosly greater than (0.8)4^k + (0.6)3^k.

???????????????????

 

[Sirius Black]

hey, are u able to remember some questions in the exam? coz we havn't done ext 1 trial yet. heaps of thanks.

Throw some numbers at me and I'll be able to tell you if thats what I got.

 

[withoutaface]

for the induction question
c how u get:
5.5^k > 4.4^k + 3.3^k

can u divide it all by 5. ending with:

5^K > (0.8)4^k + (0.6)3^k

then u can say, seeing as though 5^k > 4^k + 3^k, then it is obviuosly greater than (0.8)4^k + (0.6)3^k.

???????????????????

nah you sub in from the S(k) thing that 5^k>4^k+3^k

5^k+1
5*5^k
sub in and you get that this is less than 5^k+1, thus if this works then 5^k+1 must work
5(4^k+3^k)
now 5*4^k>4*4^k=4^k+1
and 5*3^k>3*3^k=3^k+1
5*3^k+5*4^k>3^k+1+4^k+1
:. 5^k+1>4^k+1+3^k+1

 

[Sirius Black]

Hi, Withoutaface, would u plz post up the Q7 the two projectile one here? i am quite interested in it

 

[za]

doesnt make sense to me .
dont worry i ll try work it out

 

[withoutaface]

Hi, Withoutaface, would u plz post up the Q7 the two projectile one here? i am quite interested in it

I dont have them, nor can I remember what they specifically were, sorry.

 

[acmilan]

From that rate of change of surface area if i remember correctly i got -5 cm/s. Did anyone else get that

 

[za]

yeah i think i got that as well

 

[kheir]

was the volumes answer 2pi squared ova 3

 

[snoopwogg]

Prove:
5.5^k - 4.4^k - 3.3^k > 0

3.5^k + 2.5^k - 3.4^k - 1.4^k - 3.3^k > 0
3(5^k - 4^k - 3^k) + 2.5^k - 1.4^k > 0
( > 0 ) (5^k is always > 4^k for the given domain, hence, 2.5^k > 4^k, and therefore, 2.5^k - 4^k > 0 )

 

[za]

yeah it was 2(pi^2)/3

 

[coroneos]

yeah it was 2(pi^2)/3

that's not what i got >_<

 

[withoutaface]

Both of those answers sound right to me.

 

[ToO LaZy ^*]

From that rate of change of surface area if i remember correctly i got -5 cm/s. Did anyone else get that

yay!..........

 

[kpq_sniper017]

yeah it was 2(pi^2)/3

i got 3pi²/2...lol

was that the one where u had to rotate the inverse cos function???

 

[kpq_sniper017]

:.dx/dt=v
dt/dx=1/v
then integrate, find the constant, and simplify.

damn it!
it's so easy now...took me one minute to do it in front of the computer....damn....3 marks i could so easily have got - would have been 78/84!!
ah well, too late now.

i wrote some "working" to see if i could get a mark....i just wrote x=|v dt and i wrote a couple of other lines of working....do u reckon i could get 1 mark?? i'm remaining hopeful, but i'm not expecting much.