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Composite and Inverse Functions Introductory — Free MYP4 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 f(x)=x+1 (solid curve), the line y=x (dashed), and a dotted curve that is the reflection of f across y=x.
a
Explain the reflection property that connects a function to its inverse, as illustrated in this graph. [1]
b
Show that the inverse of f(x)=x+1 is g(x)=x2−1 with domain x≥0. [1]
c
The dotted curve is proposed as a model for a physical process that only produces non-negative outputs. Assess whether g(x)=x2−1 with domain x≥0 is an appropriate model for this constraint. [1]
Solutions
3QuestionChecking if Two Functions Are InversesAssessment Practice
8 marks~12 minCriterion D
A pharmaceutical company stores vaccines at temperatures between 2∘C and 8∘C. Their international storage log records only integer Fahrenheit temperatures. The conversion formulas are C=95(F−32) and F=59C+32.
a
Show that the two conversion formulas are inverse functions by computing both compositions C(F(C)) and F(C(F)). Clearly show each algebraic step. [3]
b
Explain how recording only integer Fahrenheit values introduces error in the corresponding Celsius temperatures. Support your explanation with a numerical example. [2]
c
The storage log shows Fahrenheit readings ranging from 35∘F to 46∘F. Convert these endpoints to Celsius, then advise the company whether this Fahrenheit range should be accepted as sufficient to guarantee that vaccines remain within the required 2∘C to 8∘C safe storage range. [3]
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]