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What can go in, and what can come out?

Practice section 2 of 2

Questions 7–11 in this collection

Practice questions

Worked example · 1 of 5

Repeat the defining interval without losing endpoints

Open question

It is given that f(x)={3+x0<x≤2,7−x2<x≤4,f(x)=\begin{cases}3+x&0<x\le2,\\7-x&2<x\le4,\end{cases} and f(x)=f(x+4)f(x)=f(x+4) for all real xx. (i) Find f(1)f(1), f(8)f(8) and f(29)f(29). (ii) Sketch y=f(x)y=f(x) for −3<x≤8-3<x\le8.

CJC · Functions · Example 12

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(i) Find the three values

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(ii) Sketch on the requested interval

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Solution

Self-practice · 2 of 5

Three ranges, three endpoint decisions

Open question

Find the range of each of the following functions.

(a) f:x↦x2+4x+3f:x\mapsto x^2+4x+3, x∈Rx\in\mathbb R, x≤−2x\leq-2.

(b) g:x↦e2xg:x\mapsto e^{2x}, x∈Rx\in\mathbb R, x>0x>0.

(c) h:x↦sin⁡xh:x\mapsto\sin x, x∈Rx\in\mathbb R, −π≤x≤π-\pi\leq x\leq\pi.

CJC · Functions · Self-Practice 3 · 2025

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Discussion practice · 3 of 5

A periodic piecewise function

Open question

It is given that

g(x)={3,0<x≤2,5−x,2<x≤4,g(x)=\begin{cases}3,&0<x\leq2,\\5-x,&2<x\leq4,\end{cases}

and that g(x)=g(x+4)g(x)=g(x+4) for all real values of xx.

(i) Find g(3)g(3), g(8)g(8) and g(101)g(101).

(ii) Sketch the graph of y=g(x)y=g(x) for −2<x≤8-2<x\leq8.

CJC · Functions · Discussion 5 · 2025

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Review practice · 4 of 5

Reduce periodic inputs and sketch a complete finite window

Open question

It is given that

f(x)={7−x2for 0<x≤2,2x−1for 2<x≤4f(x)=\begin{cases}7-x^2&\text{for }0<x\leq2,\\2x-1&\text{for }2<x\leq4\end{cases}

and that f(x)=f(x+4)f(x)=f(x+4) for all real values of xx.

(i) Evaluate f(27)+f(45)f(27)+f(45). [2]

(ii) Sketch the graph of y=f(x)y=f(x) for −7≤x≤10-7\leq x\leq10. [3]

[N2009/I/4 (i), (ii)]

CJC · Review Problems · Question 7

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Review practice · 5 of 5

Extend an inverse-cosine piece periodically and solve a threshold

Open question

It is given that

f(x)={cos⁡−1xfor 0≤x<1,π2x−π2for 1≤x<2f(x)=\begin{cases}\cos^{-1}x&\text{for }0\leq x<1,\\\dfrac\pi2x-\dfrac\pi2&\text{for }1\leq x<2\end{cases}

and that f(x)=f(x+2)f(x)=f(x+2) for all real values of xx.

(i) Sketch the graph given by y=f(x)y=f(x) for −3≤x≤4-3\leq x\leq4. [3]

(ii) For 0≤x≤40\leq x\leq4, solve the inequality f(x)>π3f(x)>\dfrac\pi3, giving your answer in the exact form. [3]

[2015/VJC/JC1MYE/2]

CJC · Review Problems · Question 8

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