Question 7
- The sum of three numbers is 81. The second number is twice the first. Given that the third number is 6 more than the second, find the numbers.
- Given the points P(3, 5) and Q ( on the Cartesian plane such that R ( is the midpoint of , find the equation of the line that passes through R and perpendicular to .
Observation
The Chief Examiner reported that performance of candidates in part (a) of this question was encouraging as many candidate could obtain three numbers. While performance in part (b) of this question was unsatisfactory as many candidates had difficulty in getting the equation of the line.
In part (a), they were expected to first x, (2x) and (2x + 6) as the three numbers. Then sum of the three numbers is given as x + (2x) + (2x + 6) = 81. Simplifying gives 5x + 6 = 81. Solving gives x = 15. Therefore, the numbers are 15, 30 and 36.
