Higher Maths Post Mortem thread

I wrote D for 20 in the exam but my friend said the answer is C because the maximum and minimum y values on the sin graph are 1 and -1.

Ah but it was a sin squared graph so -1 becomes 1 and all negatives become positive.

Reply 101

Marcus4004

2

Original post by soup

That's what I got except 20D

All same, except 20D the g(x) has to be greater/equal to 0 as it is squared.

Reply 102

scotland369

2

Original post by chr1stopher11

Did you do top curve - bottom curve for this question?

I did straight line minus curve (between 3 and 0) and curve minus straight line (between 0 and -2) :confused:

Reply 103

kpopjpop

Original post by chr1stopher11

No it will definitely not that high. A B will be about 62% or something close to it :smile:

that's still high for me lol.
I wonder if a B has ever been in the 50s...

Reply 104

Quintro

11

When you type in the function to WolframAlpha the graph goes to -1:

http://www.wolframalpha.com/input/?i=y%3D+sin^2sqrt%28x-2%29

I don't know... I wrote D because if you were squaring it it couldn't be negative?

Edit:
Although for local minima it say 0 and local maxima it says 1, which suggests D... I hope it is D anyway!

(edited 12 years ago)

Reply 105

legion99

It is D in Q20 I think because it was Sin^2, so if you had got a negative value the square would have made it positive so it could only have been between 0 and 1.

Reply 106

Marcus4004

2

Original post by scotland369

I did straight line minus curve (between 3 and 0) and curve minus straight line (between 0 and -2) :confused:

It doesn't matter which was round you do it. The answer will either be + or -. Just write a comment on your script saying it is meant to be +.

Reply 107

stephenmca

5

For Question 16.. Find the integral of 1/3x^4
would the answer not be B: -1/x^3 +c
A few of you guys seem to have different answers to me for it

Reply 108

soup

11

Original post by stephenmca

For Question 16.. Find the integral of 1/3x^4
would the answer not be B: -1/x^3 +c
A few of you guys seem to have different answers to me for it

You don't multiply by the new power, you divide by it.

Reply 109

chr1stopher11

14

Original post by Quintro

This happened to me too :frown:

I thought I was doing fine and then I ended up with like 6 and 11 or something...

I had something like root34sin(t+120.96)=2

then rearranged and got t=something wrong :s-smilie:

oh well I hope I've got 3 or 4 marks anyway for that question.

Reply 110

LonelySoul193

1

Ugh. Unbelieveable. I swear my bloody P&N prelim paper was easier -_-

Reply 111

chr1stopher11

14

Original post by scotland369

I did straight line minus curve (between 3 and 0) and curve minus straight line (between 0 and -2) :confused:

Yeah that is the correct method, I think. It is the one I did. Can't remember the answer though... mind blank.

Reply 112

tompy123

7

Hi guys!

In the second paper, the answer to question 7 is: p is greater than -23. I asked my maths teacher as soon as I came out of the exam if this was the right answer and she said it was.

Reply 113

stephenmca

5

Original post by soup

You don't multiply by the new power, you divide by it.

okay what i done was this:
1 - change to form of 3x^-4
2 - add 1 to the power and divide to get .. -x^-3
3 put the negative power on the bottom, giving the answer B.

I can't understand why so many people are getting A?

Reply 114

Marcus4004

2

Original post by stephenmca

okay what i done was this:
1 - change to form of 3x^-4
2 - add 1 to the power and divide to get .. -x^-3
3 put the negative power on the bottom, giving the answer B.

I can't understand why so many people are getting A?

1- The three stays at the bottom mate!

Reply 115

scotland369

2

Original post by chr1stopher11

Yeah that is the correct method, I think. It is the one I did. Can't remember the answer though... mind blank.

But don't you think 10 marks is a bit generous for doing that? :s-smilie:

Reply 116

soup

11

Original post by stephenmca

okay what i done was this:
1 - change to form of 3x^-4
2 - add 1 to the power and divide to get .. -x^-3
3 put the negative power on the bottom, giving the answer B.

I can't understand why so many people are getting A?

It isn't 3x^-4 it would be (1/3)(x^-4) since the 3 was on the bottom.

Reply 117

Quintro

11

Original post by stephenmca

okay what i done was this:
1 - change to form of 3x^-4
2 - add 1 to the power and divide to get .. -x^-3
3 put the negative power on the bottom, giving the answer B.

I can't understand why so many people are getting A?

Step one should lead to (1/3)x^-3

Reply 118

Midnightsk010

Original post by Quintro

I wrote D for 20 in the exam but my friend said the answer is C because the maximum and minimum y values on the sin graph are 1 and -1.

It's D, my teacher checked it for us. :wink:

Reply 119

soup

11

Did anyone think for the last question that there were a lot of marks for it? I was sitting there wondering where the hell these 9 marks were going to be given.

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