Date | November 2010 | Marks available | 2 | Reference code | 10N.1.sl.TZ0.13 |
Level | SL only | Paper | 1 | Time zone | TZ0 |
Command term | Write down | Question number | 13 | Adapted from | N/A |
Question
Consider the function \(f(x) = p{(0.5)^x} + q\) where p and q are constants. The graph of f (x) passes through the points \((0,\,6)\) and \((1,\,4)\) and is shown below.
Write down two equations relating p and q.
Find the value of p and of q.
Write down the equation of the horizontal asymptote to the graph of f (x).
Markscheme
p + q = 6 (A1)
0.5p + q = 4 (A1) (C2)
Note: Accept correct equivalent forms of the equations.
[2 marks]
p = 4, q = 2 (A1)(A1)(ft) (C2)
Notes: If both answers are incorrect, award (M1) for attempt at solving simultaneous equations.
[2 marks]
y = 2 (A1)(A1)(ft) (C2)
Notes: Award (A1) for “y = a constant”, (A1)(ft) for 2. Follow through from their value for q as long as their constant is greater than 2 and less than 6.
An equation must be seen for any marks to be awarded.
[2 marks]
Examiners report
A significant number of candidates found it difficult to identify and write two equations that relate p and q. Many of those who wrote the equations were unable to solve them or use their GDC to find the values of p and q in part b). Although the question in part c) was quite standard, there were many errors in the responses. Many students wrote x = 2 or only 2 instead of y = 2.
A significant number of candidates found it difficult to identify and write two equations that relate p and q. Many of those who wrote the equations were unable to solve them or use their GDC to find the values of p and q in part b). Although the question in part c) was quite standard, there were many errors in the responses. Many students wrote x = 2 or only 2 instead of y = 2.
A significant number of candidates found it difficult to identify and write two equations that relate p and q. Many of those who wrote the equations were unable to solve them or use their GDC to find the values of p and q in part b). Although the question in part c) was quite standard, there were many errors in the responses. Many students wrote x = 2 or only 2 instead of y = 2.