Methods (CAS) 2009 exam 2 Suggested Solutions.

[scope9]

for 1e to be true, doesnt range of g(x) be contained within domain of f(x) therefore you have to alter the domain of g(x) for f(g(x)) to be true?

It is "contained"

oops totally forgot to quote this too. my bad

[VeryCrazyEdu.]

For question EA 4a. ii.

I got t=h^3/27 i thought this was right because it said for volume at t (time) in terms of h.

also in the next question, once i differentiated this and flipped it i got dh/dt...

where did i go wrong??

[scope9]

anyone know where to get the itute solution? cant find it from the web

exam 2 isnt up yet but that link posted is correct

[homghomg1]

So for question 1 e), making sqrt(X^2) = + or - x and then rejecting the minus to get a final answer of f(g(x)) = -x^2 + 6X -5, and then consequently only getting 6 -2X for part ii), will that mean losing 1 mark in each part? or lose all marks?

[scope9]

For question EA 4a. ii.

I got t=h^3/27 i thought this was right because it said for volume at t (time) in terms of h.

also in the next question, once i differentiated this and flipped it i got dh/dt...

where did i go wrong??

im no study score:50 but i do believe in 4aii its possible the question was leading onto part b which is related rates. indicating that you had to use your result from part aii in order to get b?

i dont know where you got the 27 from in your part aii...

[rohanftw]

So for question 1 e), making sqrt(X^2) = + or - x and then rejecting the minus to get a final answer of f(g(x)) = -x^2 + 6X -5, and then consequently only getting 6 -2X for part ii), will that mean losing 1 mark in each part? or lose all marks?

I did this also =(, the 2nd bit may be consequential, but it was two marks...
Was that your only mistake?
ps: don't reveal my identity.

[VeryCrazyEdu.]

For question EA 4a. ii.

I got t=h^3/27 i thought this was right because it said for volume at t (time) in terms of h.

also in the next question, once i differentiated this and flipped it i got dh/dt...

where did i go wrong??

im no study score:50 but i do believe in 4aii its possible the question was leading onto part b which is related rates. indicating that you had to use your result from part aii in order to get b?

i dont know where you got the 27 from in your part aii...

I divided the correct equation by the value for dv/dt grrrrrr

[homghomg1]

So for question 1 e), making sqrt(X^2) = + or - x and then rejecting the minus to get a final answer of f(g(x)) = -x^2 + 6X -5, and then consequently only getting 6 -2X for part ii), will that mean losing 1 mark in each part? or lose all marks?

I did this also =(, the 2nd bit may be consequential, but it was two marks...
Was that your only mistake?
ps: don't reveal my identity.

rohan hardikar

part a) was 2 marks, so im thinking we should get the mark for subbing in f(x^2)
other mark would've been for correctly simplifying to |x| etc..
for part b) you essentially needed 2 solutions, -6 -2x and 6 -2x
we got one answer right, and our method was correct so surely we will get 1 mark for this

oh, and this plus Q14 on multiple choice were my only mistakes. calc says dy/dx = 0 at x = 0, i didn't realise it was a cusp. Calculator should've known and told me it was undefined :/.... so I put B instead of D

[simpak]

So for question 1 e), making sqrt(X^2) = + or - x and then rejecting the minus to get a final answer of f(g(x)) = -x^2 + 6X -5, and then consequently only getting 6 -2X for part ii), will that mean losing 1 mark in each part? or lose all marks?

I did this also =(, the 2nd bit may be consequential, but it was two marks...
Was that your only mistake?
ps: don't reveal my identity.

rohan hardikar

part a) was 2 marks, so im thinking we should get the mark for subbing in f(x^2)
other mark would've been for correctly simplifying to |x| etc..
for part b) you essentially needed 2 solutions, -6 -2x and 6 -2x
we got one answer right, and our method was correct so surely we will get 1 mark for this

oh, and this plus Q14 on multiple choice were my only mistakes. calc says dy/dx = 0 at x = 0, i didn't realise it was a cusp. Calculator should've known and told me it was undefined :/.... so I put B instead of D

For that, I drew my graph correctly but for some stupid reason it didn't click that both lines had a negative gradient.
So only one of my lines is correct, and I stated the domain for it.
One mark, or no marks?

[homghomg1]

oh I'm non cas, there was no graph for me

[Stroodle]

Nice work TT. Thanks man!

[NE2000]

So TT do you agree about the interpretation of 3cii?

[TrueTears]

So TT do you agree about the interpretation of 3cii?

Hmm, a lot of people at my school had same as me, but some also used the probability in c i). I'm not sure myself...

[rohanftw]

So for question 1 e), making sqrt(X^2) = + or - x and then rejecting the minus to get a final answer of f(g(x)) = -x^2 + 6X -5, and then consequently only getting 6 -2X for part ii), will that mean losing 1 mark in each part? or lose all marks?

I did this also =(, the 2nd bit may be consequential, but it was two marks...
Was that your only mistake?
ps: don't reveal my identity.

rohan hardikar

part a) was 2 marks, so im thinking we should get the mark for subbing in f(x^2)
other mark would've been for correctly simplifying to |x| etc..
for part b) you essentially needed 2 solutions, -6 -2x and 6 -2x
we got one answer right, and our method was correct so surely we will get 1 mark for this

oh, and this plus Q14 on multiple choice were my only mistakes. calc says dy/dx = 0 at x = 0, i didn't realise it was a cusp. Calculator should've known and told me it was undefined :/.... so I put B instead of D

rofl wtf, exactly same I also stupid mistaked MC 14
so we did the same in q3.
then.. I somehow decided the distance from 2 and 2-2root(3) was 4-2root3

[TrueTears]

So TT do you agree about the interpretation of 3cii?

Well itute solutions are up and they did it my way:
so yeah I'm not not sure myself now...