exam1 thoughts + answer

[joechan521]

i liked this exam, not too hard and not too easy.
many people did well in my class.
here are my answers that i wrote down on the formulae sheet and took out, but dont have working outs...
correct me if im wrong

Q1 2CIS[PI/2]
Q2 b) z= 2i, -2i, rt5 - i
Q3 y=3x-3
Q4 volume = [pi loge 3]/2
Q5 a) a= -8/3 m/s^s
b) mu = 8/[3g]
Q6 a) r(t) = 2cos[2t]i+3sin[2t]j
b) [x^2]/4 +[y^2]/9 =1  ( i wrote the domain and range wrong for this q, do u think they will take away marks?)
c) graph of half elipse
Q7a) 131/110
b) loge(1.2)+1
Q8b) y=tan[x/2-pi/4]
Q9 a= -r
Q10 sinx= 1/3

Made sticky by Ahmad

[AppleXY]

Yeah, i was thinking, where have all the spesh people gone?! oh btw , its mu not mew. Corrected.

[BenBenMan]

It was tricky but not bad .. however I know I screwed up the last question (got a really messy quadratic, didn't realise you had to get cos2x then from that get sinx ..) and the solving the polynomial over C in question 2. Plus I kinda borked the slope field. Meh, oh well, I think I did well enough.

[enwiabe]

I dropped a mark on the last question by subbing into an equation with the wrong value. Stupid stupid stupid stupid.

[joechan521]

It was tricky but not bad .. however I know I screwed up the last question (got a really messy quadratic, didn't realise you had to get cos2x then from that get sinx ..) and the solving the polynomial over C in question 2. Plus I kinda borked the slope field. Meh, oh well, I think I did well enough.

i was able to solve it with quadratic,
found tanx from double angle formulae, then draw the triangle to find sinx

anyone know whether i'll loss mark for writing down the wrong domain and range, when they are not asked for?

[cara.mel]

I am glad I didn't die ^_^
7b I knew I got wrong about 2 minutes after I left the room, forgot about the +1 xDxD
Q8 I was like 'omg. Go back to exam 2 you stupid freaking slope field'. Made a decent attempt at it though
Q10 I think I have done completely wrong now xD
I tried to get in form a tan^2 x + b tan x + c, do quad stuff, get tan x, then draw triangle for sin x. My answer had a sqrt in it =/

[Ahmad]

Full marks, it seems. Hope my working out is OK for examiners. Discuss more soon, gotta eat.

[Matt89]

anyone know whether i'll loss mark for writing down the wrong domain and range, when they are not asked for?

I dont think so. But if you got the domain and range wrong, the part where you graph it would be wrong so you'd lose marks there

Q9 a= -r

Did anyone else find that question a little too easy? I'm not trying to sound smart, but it was worth 3 marks and barely required any working out.

[Ahmad]

It was tricky but not bad .. however I know I screwed up the last question (got a really messy quadratic, didn't realise you had to get cos2x then from that get sinx ..) and the solving the polynomial over C in question 2. Plus I kinda borked the slope field. Meh, oh well, I think I did well enough.

i was able to solve it with quadratic,
found tanx from double angle formulae, then draw the triangle to find sinx

anyone know whether i'll loss mark for writing down the wrong domain and range, when they are not asked for?

Sometimes and examiners are picky and want domain for these. It was 2 marks, so I assume they probably only want the cartesian equation, and PERHAPS the domain. I didn't put the range, I think the range is tested out in the graph anyway.

[BenBenMan]

Did anyone else find that question a little too easy? I'm not trying to sound smart, but it was worth 3 marks and barely required any working out.

That one was too easy.

[joechan521]

anyone know whether i'll loss mark for writing down the wrong domain and range, when they are not asked for?

I dont think so. But if you got the domain and range wrong, the part where you graph it would be wrong so you'd lose marks there

Q9 a= -r

Did anyone else find that question a little too easy? I'm not trying to sound smart, but it was worth 3 marks and barely required any working out.

i drew the graph with x{ [-2,2] y{[0,3]

yeah Q9 was too easy, i didnt write much working out either
i think u need to write something like x'=-y y'=x

[enwiabe]

Depends how you attacked it. If you assumed x = cost and y = sint, then you'll lose a mark or two. You were supposed to work in terms of 'x', 'y' and 't' only, and not introduce a foreign function, I believe. That's why it was worth 3 marks. You had to show it for all 'x' and 'y', not a doctored function.

[joechan521]

the slope field was a strange question.
i drew lines at all 25 points,
let the numbers be the gradient
2  2  2  2  2
1  1  1  1  1
.5 .5 .5 .5 .5
1  1  1  1  1
2  2  2  2  2
is this correct?

Err.. 2.5 instead of 2? lol it should be 2.5! i thought it was 2, but anyway examiners can't tell from the drawing

[Matt89]

Did anyone else have trouble drawing the Tan graph on the slope field? without a scale in terms of pi, i had no idea  :?

[joechan521]

Did anyone else have trouble drawing the Tan graph on the slope field? without a scale in terms of pi, i had no idea  :?

just draw roughly and let pi equal a bit more than 3

did u guys draw asymptoes/intersects ? its a bit too much working for a 1mark question.