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General Mathematics Paper 2,May/June. 2009  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 Main
General Comments
Weakness/Remedies
Strength








Question 9

Simplify   x + 2     -   x + 3
                 x - 2           x - 1

(a)The graph of the equation y = A x2 + B x + C passes through the points (0, 0), (1, 4) and (2, 10).  Find the:
(i)     value of C;
 (ii)    values of A and B;
(iii)    co-ordinates of the other point where the graph cuts the x-
          axis.

_____________________________________________________________________________________________________
Observation
 

The part (a) of this question attracted majority of the candidates.  However, many of them were unable to get the L.C.M.  A few others cross multiplied both sides of the minus sign.  They were expected to use  (x - 2)(x - 1) as L.C.M and obtained

(x+2(x-1) – (x+3)(x-2)     =       4
    (x - 2)  (x – 1)                  (x - 2)(x - 1)

In part (b), candidates’ performance was fair.  However, majority of the candidates appeared not to be familiar with coordinate of points on a graph.  To find point C, candidates were expected to use x = 0 and y = 0 to get c = 0.  Similarly, substituting 1 for x and 4 for y as well as 2 for x and 10 for y gives two equations in A and B i.e. A + B = 4; 4A + 2B = 10.  Solving these equations simultaneously gave A = 1, B = 3, which gave the equation as y = x2 + 3x.

To get the 2nd point of intersection with the x – axis, put y = 0, in the equation to get x2 + 3x = 0.  Solving this equation gave x = -3, Thus the required point = (-3, 0)

 

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