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General Mathematics Paper 2, Nov/Dec. 2008  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 Main
General Comments
Weakness/Remedies
Strength
Question 8

(a)        Copy and complete the table of values for the relation:
y = -3x2 + 12x  for -2 < x < 6.
           

x -2 -1 0 1 2 3 4 5 6

y

-36

 

0

 

 

 

0

 

 

(b)  Using a scale of 2cm to 1 unit on the x-axis and 2cm to 5units on the y-axis, draw the graph of y = -3x2 + 12x.
(c) On the same axes, draw the line y = 5x – 10.
(d) On your graph, shade the region for which 7x + 10 > 3x2.

_____________________________________________________________________________________________________
Observation

Many candidates attempted the question and perform very well in it. They were able to complete the table of values and plot the graphs correctly.  However,

some of the candidates could not shade the required region correctly. Rearranging the equation 7x + 10 >  3x2 gives -3x2 + 12x >  5x – 10.Thus the required area is that between the points of intersection of -3x2 + 12x and 5x – 10 where the graph of -3x2 + 12x is higher than that of 5x – 10.
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