Posted in A-Level, JC Math (H2/H1)

Suggested Answers to 2014 A Level H1 Math 8864

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Hi, we tried to rush it out. This might not be the most appropriate suggested solutions. Feel free to comment and discuss. Let me know if I make mistakes. Thanks!

Also, we might not respond too fast as we will be trying to do the paper 2 for h2 math later too.

ERRATA:

4(ii) I made a silly mistake substituting the equations back in. You should get (4, 18) and (8,6) as the answers.

Many thanks to those who point out my mistakes.

 

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Posted in A. Math

Suggested answers to GCE O Level 2014 A. Math (4047) Paper 2

1(i)  When t = 0, 20 + A = 80, so A must be equal to 60.

1(ii)  k = 0.288 (to 3 SF)

1(iii) Since t > 3.82, it is safe to give the food 4 min after removal from the microwave.

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2(i) Remainder = – 12

2 (ii)  f(-2) = 0, so (x+2) is a factor of f(x).  Solving f(x) = 0, x = -2, 1/2 or 3.

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3(i)  Length of rectangle = 9/2 + Sqrt(3)/6

3(ii) c = -1

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4(I) 2.25 4

(ii) 8x^2 + 5x + 64 = 0

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5(a) x^2 – 8x + 32 = 0. No real solution because discriminant is less than 0.

5(b) y = 1/x^2

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6(I) Use the fact that triangle ACE is isosceles and the alternate-segment theorem to state that angle ACE = angle ABC. Angle DEF = angle ECA + angle EAC.

6(ii) angle DFE = 2 x angle ACB.

6(iii) Use the fact that angle BAC = 180 deg – (angle BAF + angle CAE).

So 2 x (angle BAC) = 360 deg – 2(angle BAF + angle CAE).

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7(I)  p = 3 and q = 2

7(ii) (a) increasing

7(ii) (b) decreasing

7(iii) It is a maximum point

7(iv) 0

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To be continued

Posted in A. Math

Suggested answers to GCE O Level 2014 A. Math (4047) Paper 1

1.  k = -2

2.  sqrt(26)/26

3.  1.75

4.  -3/x   –  2/x^2  +  4/(x-2)

5(i) v = 0.263

5(ii) around v = 0.231

5(iii) around f = 0.120

6. (i) Remember that when there is a mixture of trigo functions which cannot fit into a single trigo identity, convert all the given trigo functions into sine and cosine. Start with the LHS, the more complicated expression.  You will reach the key stage where

LHS = 1 / [(1 – sin^2@)/(sin@cos@)] = 1/ (cos^2@/sin@cos@) = 1/(cos@/sin@) = tan@

6(ii) acute angle, so @ = 1.05.

7(i) A = (h, 2h);  B = (7h/4, 2h);  C = (h, h/2)

7(ii) Area of trapezium = 21 sqr units.

8. Integrate f'(x) to get f(x) with a +c. Use f(pi/2) = 0 to get c = 1/4. Differentiate f'(x) to get f”(x)= 4cos4x + 2sin2x. Proceed to add f”(x) to 4f(x) to get the RHS.

9(i) Pure inequality question. Solve 2x^2 + 5x – 12 > 0 by sketching a quadratic graph. Ans:  {x :  x < -4  U  x > 3/2}

9(ii) Show that the (b^2 – 4ac) of (4x^2 + 4x + 1 = 0) is zero.

9(iii) a = -1.

 

To be continued ….

Posted in Exam Answers

Suggested answers to GCE O Level 2014 Math (4016) Paper 2

Related links:

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1(a) x < 1/2

1(b)(i) W = 126

1(b)(ii) u = +- Sqrt(v^2 – 2W/m)

1(c)  2x / (x – 4y)

1(d) x = 7 or -1

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2(a) 4.12 x 10^10 kWh

2(b) 40.5% (to 3 SF)

2(c) 1439 kWh (to the nearest kWh)

2(d) 26.2% (to 3 SF)

2(e) 5725 GWh (to the nearest GWh)

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3(a) p = 11.4

3(b) cubic graph

3(c) Near exact answers are x = -1.54, 3.84 or 1.69 (examiners accept answers within a small range)

3(d) Exact answer for the gradient is -5.2 (examiners accept answers within a small range).

3(e) (i) straight line with positive gradient intersects the curve at one point.

3(e)(ii) Near exact answer is (4.24, 0.83) (examiners accept answers within a small range)

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4(a) 83 deg

4(b) Use AA property

4(c) Triangle EAB

4(d)(I) 5:3

4(d)(ii) 82.62 cm squared

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5(a)(I) (-6, -7) in vertical form (2×1 matrix)

5(a)(ii) 9.22 units

5(a)(iii) (4, 8.5)

5(b)(I) 4y + 3x = 16

5(b)(ii) (-2, 5.5)

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To be continued …….

 

Posted in O Level

Suggested answers to GCE O Level 2014 Math (4016) Paper 1 (via crowdanswering)

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1) sqrt (0.48), 0.702, 27/38, 0.61

2) 3.90 swiss francs

3a) 629.25

3b) 630

4) 47.9 deg or 132.1 deg (or 0.836 rad or 2.31 rad)

5) zero hours not offered; the choices given for the intervals for the number of hours spent are not continuous; time limit, such as per day or per week, not set.

6) – 1/3 (corrected)

7) 112

8) 79.4%

9a) 1000

9b) 200%

10a) 32 sec

10b) 7.5 sec

11) $78.50

12) x = 3 cm, y = 5 cm, z = 15 cm

13) $7500

14a) 1/3 (b a)

14b) vector DC cannot be expressed as k(vector OA), so vectors DC and OA are not parallel.

15a) Two circles overlapping

15b) {4,6,7,8,9,10,11}

16a) 3b^5/2a

16b) (8x-5)/(x-3)^2

17a) a = 5, b = 19, c = 26

17b) 7n – 2

c) There is no integer value of n such that 7n-2 = 109

18a) 8  11/18 m/s

18b) 9 min 43 sec

19a) graph curves upwards, passes thru origin

19b) s = 2.25 t^2

19c) 2.98 sec

20a) 1/4

20b) 1/16

20c) 55/64

21ai) (2.6 4.3 6.8) as in 3×1 matrix

21aii) E = (151.4 135.4) as in 2×1 matrix

21aiii) It represents the masses of the coins saved by Lin and Hadi respectively

21b) (10 20 100) as in 3×1 matrix

22) $644.17

23a) 314 cm^2

23b) 5 cm by 7 cm by 11 cm

23c) 42

24a) 9(x-1)

24b) 57 cm

24c) 196 cm^2

Ad hoc O Level Math or Physics Tuition from 20 Oct to 26 Oct 2014

Suggested answers to GCE O Level 2014 Math (4016) Paper 2

 

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Posted in A-Level, Exam Papers

Suggested Answers to 2013 A Level H2 Math 9740 Paper 1 (11 Nov)

MOCK EXAMS FOR SCIENCE PRACTICAL

 

 

 

END OF PAPER

Note: The above answers had been hurriedly worked out by Mr Teng, our H2 Math tutor.

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Errata: question 7(iii)
This question is really confusing due to the word “before”. However, after much discussions, Mr Teng concludes that he is wrong. The answer should be n=12. If you put the emphasis on how many MUST be cut off, 12 will be the correct answer. If you’re my student, you will know that my English is terrible. Haha.

Question 6(iii)) should λ = 8μ/7.

Question 9(iii) due to the lousy app should be 24n.

Disclaimer: Question 3
The line y=1 was drawn as part of my solution to (ii). So long as the diagram is clearly labeled, there should be no issues.

Any more issues, please let me know. Lastly, big thank-you to all the j1 and j2s who helped me clarify and explain the English behind the statement. And do watch out this space for P2!

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(1) What to do if your A-level results are bad …

(2) A-Level Results: What to do if you get BAD or DEAD, i.e., the ‘middle class’

(3) Beware the critical years in math education …

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CALL 65694897 OR SMS 98530744 OR 97860411.

 

 

 

 

 

Posted in A. Math, Administrative, Sec Math

Sec Math Textbook Solutions

If you are looking for fully-worked solutions to problems found in commonly used mathematics (Additional or Elementary) textbooks in Singapore, you can check out this wonderful website created by Lee Chu Keong, a lecturer at the Nanyang Technological University: http://www.openlysolved.org

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