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Composite and Inverse Functions Introductory — Free MYP5 Mathematics (Extended) Practice Questions
1QuestionEvaluating Composite FunctionsAssessment Practice
2 marks~3 minCriterion A
A surveyor uses a 3-4-5 right triangle to set a reference angle θ, where θ is the angle opposite the side of length 3.
The functions f(x)=sin(x°) and g(x)=x+30 model how the surveyor adjusts bearing angles.
Calculate the value of f(g(θ)), giving your answer to 3 significant figures. [2]
Solutions
2QuestionChecking if Two Functions Are InversesAssessment Practice
3 marks~5 minCriterion C
The graph shows h(x)=21x+2 (solid line), the line y=x (dashed), and three points claimed to belong to a function p(x): (0,−4), (2,0), and (4,4).
a
Calculate the coordinates of the points on h(x) at x=0, x=2, and x=4. [1]
b
Deduce the coordinates that the inverse of h(x) must pass through by reflecting your points from (a) across the line y=x. [1]
c
Justify whether p(x) is the inverse of h(x), referring to your results from (b). [1]
Solutions
3QuestionConcept of Inverse FunctionsAssessment Practice
6 marks~9 minCriterion D
A car's fuel efficiency is modelled by the function
f(x)=12x
where x is the distance travelled in kilometres (km) and f(x) is the fuel used in litres (L). The model assumes constant driving conditions throughout any journey.
a
Determine the inverse function f−1(x) and explain what it represents in this context. [2]
b
A driver has 30 L of fuel available. Using f−1(x), calculate the maximum distance the driver can travel. [2]
c
The driver plans a 400 km motorway journey followed by a 20 km urban leg. Advise the driver whether 35 L of fuel is sufficient for the full journey, justifying your answer with reference to the model's assumption of constant driving conditions. [2]
Solutions
4QuestionEvaluating Composite FunctionsAssessment Practice
6 marks~9 minCriterion B
A computer simulation models the spread of a digital signal through a network. At each step, the signal passes through two filters in sequence: filter f doubles the strength, then filter g adds 1 unit. Formally, f(x)=2x and g(x)=x+1, giving composite function h(x)=g(f(x)). The simulation begins at strength x0=1 and updates by xn+1=h(xn).
a
Calculate x1, x2, x3, and x4. [2]
b
Deduce a general formula for xn in terms of n. [2]
c
The network has a maximum capacity of 1000 units. Justify whether this capacity is exceeded within the first 8 steps of the simulation. [2]