2008 Mathematics Paper Questions (1 Viewer)

[imoO]

Hey guys, just a few questions I would like to request solutions for, because I've been unable to to do them Here is the paper - Download 2008HSC-mathematics.pdf for free on uploading.com Questions- 5 a) 8 a) iii)how do prove it's local maximum and not global? 9 c) ii) 10 a)no clue on how to do the whole question...i think im meant to differentiate in part ii), but that turned out weird. cheers

 

[x_symphonic]

if its the actual 2008 hsc paper then answers are here itute.com FREE maths exams

 

[daniieee]

if its the actual 2008 hsc paper then answers are here itute.com � FREE maths exams

Thanks for the link! I wasn't after the 2008 answers but rather 2007. What the frig is with 9c. Anyhow thanks again.

 

[tonyharrison]

Well for (8)(a)(iii):
f'(x) = 4x^3 - 16x
Stationary points at f'(x) = 0
0 = 4x^3 - 16x
0 = x (4x^2 - 16)
Therefore:
x = 0
OR
4x^2 = 16
x = 2

At (x = 0):
f'(x) = 0 (possible point of inflexion)
Do concavity check, i couldn't be fucked but you can probs assume it is one
At (x = 2)
f'(x) = -16
f'(x) < 0 (maximum turning point)

The endddd!!!

 

[daniieee]

Well for (8)(a)(iii):
f'(x) = 4x^3 - 16x
Stationary points at f'(x) = 0
0 = 4x^3 - 16x
0 = x (4x^2 - 16)
Therefore:
x = 0
OR
4x^2 = 16
x = 2

At (x = 0):
f'(x) = 0 (possible point of inflexion)
Do concavity check, i couldn't be fucked but you can probs assume it is one
At (x = 2)
f'(x) = -16
f'(x) < 0 (maximum turning point)

The endddd!!!

You should have gotten 3 stationary points, with one maximum at (0,0) and two minimum turning points at (2,-16) and (-2,-16). You made an error shortly after f'(x)=0 as 4x^3-16x would have given you three x values (being a cubic). From your working you took out the x but neglected to take out the 4 as well which would've made it clearer with 4x(x^2-4) as x^2-4 gives you plus & minus 2.

The link that x_symphonic provided should have the full working.

 

[x_symphonic]

Thanks for the link! I wasn't after the 2008 answers but rather 2007. What the frig is with 9c. Anyhow thanks again.

np ^^