FOR EDEXCEL GCE Examinations Advanced Subsidiary Core Mathematics C2 Paper A MARKING GUIDE This guide is intended to be as helpful as possible to teachers by providing concise solutions and indicating how marks could be awarded. There are obviously alternative methods that would also gain full marks. Method marks (M) are awarded for knowing and using a method. Accuracy marks (A) can only be awarded when a correct method has been used. (B) marks are independent of method marks. Written by Shaun Armstrong Solomon Press These sheets may be copied for use solely by the purchaser’s institute. C2 Paper A – Marking Guide 1. (a) f(−2) = −35 (b) = f( 23 ) ∴ −24 − 8 − 2k + 9 = −35 k=6 B1 8 = 3( 27 ) − 2( 49 ) + 6( 23 ) + 9 = 2. x 2x −2 −1 1 4 1 2 area ≈ 1 2 = 3. tan2 θ = π 6 , (a) (b) 5. (a) π 6 (5) B1 B1 M1 A1 A1 (5) M1 A1 π 6 − π or π − π 6 , − π6 B1 M1 5π 6 , A2 8 8 M1 A1 x = 0.001 (1.003)8 ≈ 1 + 0.024 + 0.000 252 + 0.000 001 512 = 1.024 253 5 (8sf) B1 M1 A1 (i) M1 A1 = 2 log3 x = 2t = 1 2 2t − log3 x log 3 9 = log3 x 2 = 1 2 t M1 A1 (7) M1 A1 8 3 M1 8 3 radius = 8 3 x = 3 = 18.7 , 25 + 1 = M1 A1 26 M1 A1 (b) (−4, 7), LHS = (−4 + 3)2 + (7 − 2)2 = 1 + 25 = 26 ∴ lies on circle B1 (c) grad of radius = 7−2 −4 − ( −3) ∴ grad of tangent = ∴ y−7= 1 5 −1 −5 (7) M1 A1 ∴ (x + 3)2 + (y − 2)2 = ( 26 )2 (x + 3)2 + (y − 2)2 = 26 = −5 = M1 1 5 M1 A1 (x + 4) M1 5y − 35 = x + 4 x − 5y + 39 = 0 C2A MARKS page 2 (6) t=4 log3 x = (a) 2 4 M1 A1 = 1 + 8(3x) + (3x)2 + (3x)3 + ... 2 3 = 1 + 24x + 252x2 + 1512x3 + ... t= 6. + 4 + 9 = 13 1 3 (ii) (b) 8 9 or 5.63 (3sf) θ = − 5π6 , − π6 , 4. 1 2 − 1 3 tan θ = ± θ = 0 1 8 9 × 1 × [ 14 + 4 + 2( 12 + 1 + 2)] 5 85 M1 A1 A1 Solomon Press (10) 7. (a) (b) 2x2 + 6x + 7 = 2x + 13 x2 + 2x − 3 = 0 (x + 3)(x − 1) = 0 x = −3, 1 ∴ (−3, 7), (1, 15) area under curve = M1 M1 A1 A1 1 ∫ −3 (2x2 + 6x + 7) dx = [ 23 x3 + 3x2 + 7x] −13 M1 A2 = ( 23 + 3 + 7) − (−18 + 27 − 21) = 22 23 M1 area of trapezium = 1 2 × (7 + 15) × 4 = 44 shaded area = 44 − 22 23 = 21 13 8. (a) a(r 4 − 1) r −1 M1 A1 2 = 10 × a(r − 1) 9. A1 M1 M1 A1 a(33 − 1) = 26 3 −1 26 a= =2 13 M1 A1 A1 (c) 6 S6 = 2(3 − 1) = 728 (a) area = 2xy + ( 12 × x2 × 0.5) = 2xy + M1 A1 3 −1 ∴ y= 50 − 14 x 2 2x = 25 x − 1 8 P = 2x + 4y + (x × 0.5) = (b) (c) 25 − 18 x) x 100 − 12 x = 2x x = 5 2 x + 4( = 5 2 x+ dx 2 x 2 = 50 x 5 2 = 2( 5 2 ) + 100 5 2 (11) M1 A1 x + 4y M1 M1 + 100 x A1 M1 A1 M1 A1 = 200x−3 when x = 5 2 , (d) 1 4 dP = 2 − 100x−2 dx for minimum, 2 − 100x−2 = 0 x2 = 50 x = 50 or 5 2 d2 P (11) B1 M1 r −1 r4 − 1 = 10(r2 − 1) r4 − 10r2 + 9 = 0 (r2 − 1)(r2 − 9) = 0 r2 = 1, 9 r = ± 1, ± 3 r>1 ∴r=3 (b) B1 M1 d2 P dx 2 = 2 5 2, d2 P dx 2 > 0 ∴ minimum = 10 2 + 10 2 = 20 2 Solomon Press A1 M1 A1 (13) Total (75) C2A MARKS page 3 Performance Record – C2 Paper A Question no. Topic(s) Marks 1 2 3 4 remain. trapezium trig. eqn binomial theorem rule 5 5 6 5 6 7 8 9 logs circle area by integr. GP circular sector, max./min. problem 7 10 11 11 13 7 Student C2A MARKS page 4 Solomon Press Total 75