General Mathematics Paper 2,Nov/Dec. 2010
 Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 Main
Weakness/Remedies
Strengths
>
Question 7

(a) Copy and complete the following table for the relation y = ½x(x - 6) for -2 ≤ x ≤ 8.

(b) Using scales of 2cm to 1 unit on the x - axis, and 2cm to 2 units on the y-axis, draw the graph of the relation y = ½x(x - 6) for -2 ≤ x ≤ 8.
(c) Use the graph to find the:
(i)range of values of x for which y is negative;
(ii)minimum value of y;
(iii)roots of the equation ~x(x - 6) = 5

_____________________________________________________________________________________________________
Observation

The Chief Examiner reported that this question was attempted by majority of the candidates. Majority of those who attempted it were reported to have completed the table of values and drew the graph correctly. However, reading and drawing inferences from the graph posed some problems to candidates. While only a few candidates were reported not to have plotted the points correctly, majority of them were reported not to have determined the required range of values correctly. Finding the roots of the equation½x(x - 6) = 5 also posed some problems to these candidates. They were expected to complete the table as follows:

The range of values of x for which y is negative can be gotten from the graph by noting the x-coordinates of the part of the graph that fell below the x-axls, In this case, the range was o < x < 6. The minimum value obtained from the graph was -4.5 while the roots of the equation was x = -1.35 and 7.35.