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# GCE O Level Oct/Nov 2012 A-Maths 4038 Paper 1 Suggested Answers & Solutions

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Tuition given in the topic of Miss Loi the Tutor from the desk of at 7:05 pm (Singapore time)

Updated on

TWAAANG! …

*hurried footsteps*

[Enter CHIEF DISCIPLE]

The Chief Disciple of The Temple appeared and rushed forward to lay prostrate before the High Priestess.

Oh forgive me! My High Priestess 教主!

I did not anticipate the unprecedented traffic that descended upon our website last Wednesday night!

She paused her guzheng playing, and glanced momentarily at the Chief Disciple.

*sigh*

The two EMaths papers last week were apparently so easy to the point that the A1 cut-off mark is now firmly believed to be well into the 90s.

That had led to a massive “how many marks have I lost/can be saved” marks-counting exercise, resulting in comments that took me three nights to go through (and still continuing 🙁 )

Such is the mess of our academic 江湖 these days.

Suddenly the heavens opened, and a thunderstorm pelted the Temple’s ornate roof.

My High Priestess 教主! I have incoming news from the AMaths front!

Something about EMaths sine rule & a distance traveled by a particle …

Yes I know …

Once again, she began to play her guzheng faster and faster …

twaaang! twaaang! twaaang! TWAANG! TWAANG! TWAANG!

… until the following shot out from within the strings of the musical instrument.

Click the button and grab it here!

Access it here if you’re having trouble accessing it on Facebook using your state-of-the-art smartphone 🙁

Next, she threw out another swarm of daggers …

Now for Paper 2: Here’s a list of possible topics that may appear for tomorrow’s AMaths Paper 2.

1. Polynomials & Remainder Theorem
2. Logarithmic & Exponential Functions
3. Further Trigonometry esp R-Formula
4. Curves
5. Maxima/Minima Problems
6. Quadratic Equations & Inequalities (Discriminants etc.)
7. Plane Geometry aka the 阴阳眼 eyesight test
8. Coordinate Geometry
9. Integration: Area of region under curve
10. Integration/Differentiation of Partial Fractions
11. Modulus Functions
12. Increasing & Decreasing Functions

Last important tip for today, tomorrow’s an
8AM Morning Paper!!!

ALL THE BEST for AMATHS PAPER 2 & GANBATTE!

[EXEUNT]

### Revision Exercise

To show that you have understood what Miss Loi just taught you from the centre, you must:

1. Mark commented in tuition class

2012
Oct
29
Mon
7:13pm

1

Hi! For qn 5 on graph, i did not start from origin(0,0), i started from (0,1). Is it ok?

i read the y intercept wrongly (i think i read it as 2.5 when it should be 2.05) , so i calculate my part ii ans as

ln(M) = 2.5
M = 14.++
Will i get 1m for this method?

iii) Following up, i got wrong too as i used after half M used,

M= 0.5(14.++)
M= 7.++
ln(7.++) = VALUE
i followed this value from my yintercept graph, so i got time as 0.3++, will i also get 1m for my method!

2. Hallowed hood commented in tuition class

2012
Oct
29
Mon
7:57pm

2

For question 13, part ii, can I show alternatively that as long as the gradient of CP is equal to the gradient of OC, then it means that the line CP passes through the origin?

I would appreciate if you could reply soon. Thanks a lot.

3. Ced commented in tuition class

2012
Oct
29
Mon
8:41pm

3

Hi,

I misread question 11 as roots of x² − 16x + 52 = 0 are α and β, find a quadratic equation whose roots are α + 3β and 3α + β. I did the question as per normal.

Will I be able to get method marks for this question?

4. Rebecca commented in tuition class

2012
Oct
29
Mon
8:49pm

4

For question 9(i) can I differentiate using quotient rule? The answer I got is (-24t-24) over (t+1) to the power of 4. Is this correct?

Also, for question 3(ii) I forgot to write the constants. Will I get method mark out of the three marks?

Thank you

5. weineng commented in tuition class

2012
Oct
29
Mon
9:15pm

5

hi, for qn 1, dx/dt should be both 0.08 and -0.08.
They question said changing, not increasing nor decreasing. am i wrong?

• 2012
Oct
31
Wed
12:20am

5.1

@weineng: Q1: Ok to sort this ang moh issue out ...

Since neither "increasing" or "decreasing" is used to describe the rate in the question, a minus sign would have been placed in front of 0.4 units per sec if it was decreasing.

However, if the rate had been described as "decreasing" in the question, then no minus sign would be necessary.

Thus the rate in described in Q1 is an increasing rate.

6. Joel commented in tuition class

2012
Oct
29
Mon
9:45pm

6

For 3ii) if I had combined all the individual factors as shown in your workings to form (2x²lnx - x² + 2 c) / 4 will it be wrong?

And for 13iii) if I leave it as per normal in the unexpanded form, will I still be marked right or be deemed wrong?
Thanks

7. Raymond commented in tuition class

2012
Oct
29
Mon
9:58pm

7

Hi! I got the equation of the circle for the last part of last question in the form of (x-a)^2+(y-b)^2... but I ended up expanding wrongly. So how many marks will be deducted?

Also, for the distance travelled for kinematics, I put 3 units instead of 3m cos I did not see the unit given. How many marks will be deducted?

• 2012
Oct
31
Wed
12:40am

7.1

@Raymond: Aiyo ... if only you had left your final answer in (xa)² + (yb)² = r² form, you wouldn't have risked 1 mark being deducted for your expansion!

Q9(ii): At the very most, a 1 mark deduction from the pool of miscellaneous marks allocated for very minor infringements such as this one.

8. Ng Guan Zhi commented in tuition class

2012
Oct
29
Mon
10:14pm

8

For qn 11 if I never put =0 will marks be deducted and for the period can I leave it in degree form 720 degrees

• 2012
Oct
31
Wed
12:51am

8.1

Q11: Quite a number have committed this error since an equation is required. Not sure how many marks you will be penalised for this though (suspect just 1 mark) 🙁

Q8(ii): Generally you shouldn't answer in degrees when the function is defined in radian space 🙁

9. Donburi commented in tuition class

2012
Oct
29
Mon
10:16pm

9

Hello Ms Loi,

I would like to inquire about the questions 3ii and 5iii.

For question 3ii, If I inadvertently forget to write the Constant term, will marks be deducted? If so, how many out of the 3 marks?

For question 5iii, I only wrote down , and forgot that I had to add in , giving . In this scenario, will I get at least 1 mark, or zero due to the incomplete workings/formulae?

I hope to hear from you soon! 😀

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