Date | May 2014 | Marks available | 2 | Reference code | 14M.2.sl.TZ2.6 |
Level | SL only | Paper | 2 | Time zone | TZ2 |
Command term | Find | Question number | 6 | Adapted from | N/A |
Question
Let f(x)=pcos(q(x+r))+10f(x)=pcos(q(x+r))+10, for 0⩽x⩽20. The following diagram shows the graph of f.
The graph has a maximum at (4,18) and a minimum at (16,2).
Write down the value of r.
Find p.
Find q.
Solve f(x)=7.
Markscheme
r=−4 A2 N2
Note: Award A1 for r=4.
[2 marks]
evidence of valid approach (M1)
eg maxy value -- y value2, distance from y=10
p=8 A1 N2
[2 marks]
valid approach (M1)
eg period is 24, 36024, substitute a point into their f(x)
q=2π24(π12, exact), 0.262 (do not accept degrees) A1 N2
[2 marks]
valid approach (M1)
eg line on graph at y=7, 8cos(2π24(x−4))+10=7
x=11.46828
x=11.5 (accept (11.5,7)) A1 N2
[2 marks]
Note: Do not award the final A1 if additional values are given. If an incorrect value of q leads to multiple solutions, award the final A1 only if all solutions within the domain are given.