VCAA Specialist Mathematics Functions, relations and graphs

12 sample questions with marking guides and sample answers · Avg. score: 92.3%

Q2
2024
QCAA
Paper 1
1 mark
Q2
1 mark

Given that Ax2+3x=x6x(x2)\frac{A}{x-2} + \frac{3}{x} = \frac{x-6}{x(x-2)}, determine the value of AA.

A

4-4

B

2-2

C

22

D

44

Reveal Answer
A

4-4

Substituting A=4A=-4 and combining the fractions yields a numerator of 4x+3(x2)=x6-4x + 3(x-2) = -x-6, which does not match the required numerator x6x-6.

B

2-2

Correct Answer

Multiplying the equation by the common denominator x(x2)x(x-2) gives Ax+3(x2)=x6Ax + 3(x-2) = x-6. Expanding and comparing coefficients of xx leads to A+3=1A+3=1, so A=2A=-2.

C

22

Substituting A=2A=2 results in a combined numerator of 2x+3(x2)=5x62x + 3(x-2) = 5x-6, which is incorrect.

D

44

Substituting A=4A=4 results in a combined numerator of 4x+3(x2)=7x64x + 3(x-2) = 7x-6, which is incorrect.

Q2
2024
VCAA
Paper 2
1 mark
Q2
1 mark

Consider the function ff with rule f(x)={x2+3x10x2,xR{2}7,x=2f(x) = \begin{cases} \frac{x^2 + 3x - 10}{x - 2}, & x \in R \setminus \{2\} \\ 7, & x = 2 \end{cases}
Which of the following statements is correct?

A

The function ff is continuous.

B

The graph of y=f(x)y = f(x) has a vertical asymptote.

C

The graph of y=f(x)y = f(x) has a horizontal asymptote.

D

The graph of y=f(x)y = f(x) has a point of discontinuity.

Reveal Answer
A

The function ff is continuous.

Correct Answer

For x2x \neq 2, the function simplifies to f(x)=x+5f(x) = x + 5. Since limx2(x+5)=7\lim_{x \to 2} (x + 5) = 7, which equals f(2)f(2), the function is continuous everywhere.

B

The graph of y=f(x)y = f(x) has a vertical asymptote.

The factor (x2)(x - 2) in the denominator cancels with the numerator, creating a removable singularity rather than a vertical asymptote.

C

The graph of y=f(x)y = f(x) has a horizontal asymptote.

As x±x \to \pm\infty, the function behaves like the line y=x+5y = x + 5, meaning it approaches infinity rather than a horizontal asymptote.

D

The graph of y=f(x)y = f(x) has a point of discontinuity.

Although the rational expression is undefined at x=2x = 2, the piecewise definition explicitly fills this "hole" by defining f(2)=7f(2) = 7, making it continuous.

Q3
2025
VCAA
Paper 2
1 mark
Q3
1 mark

The graph of y=x2+abx+cy = \frac{x^2 + a}{bx + c} has an asymptote given by y=12x+14y = -\frac{1}{2}x + \frac{1}{4} and a yy-intercept of 2-2.

The values of aa, bb and cc are

A

a=2,b=2,c=1a = 2, b = -2, c = -1

B

a=2,b=2,c=1a = 2, b = 2, c = -1

C

a=2,b=2,c=1a = -2, b = -2, c = 1

D

a=2,b=2,c=1a = -2, b = -2, c = -1

Reveal Answer
A

a=2,b=2,c=1a = 2, b = -2, c = -1

Correct Answer

Correct. The yy-intercept gives ac=2\frac{a}{c} = -2. Polynomial division reveals the asymptote is y=1bxcb2y = \frac{1}{b}x - \frac{c}{b^2}, so 1b=12\frac{1}{b} = -\frac{1}{2} and cb2=14-\frac{c}{b^2} = \frac{1}{4}, yielding b=2b = -2, c=1c = -1, and a=2a = 2.

B

a=2,b=2,c=1a = 2, b = 2, c = -1

Incorrect. This option incorrectly sets b=2b = 2, which would result in an asymptote with a positive slope of 12\frac{1}{2} instead of 12-\frac{1}{2}.

C

a=2,b=2,c=1a = -2, b = -2, c = 1

Incorrect. With c=1c = 1 and b=2b = -2, the yy-intercept of the asymptote would be cb2=14-\frac{c}{b^2} = -\frac{1}{4}, which contradicts the given value of 14\frac{1}{4}.

D

a=2,b=2,c=1a = -2, b = -2, c = -1

Incorrect. With a=2a = -2 and c=1c = -1, the yy-intercept of the function would be ac=2\frac{a}{c} = 2, which contradicts the given yy-intercept of 2-2.

Q15
2021
QCAA
Paper 1
4 marks
Q15
4 marks

Use partial fractions to determine 4x17x2x6dx\int \frac{4x-17}{x^2 - x - 6} dx, where xR,x2,x3x \in R, x \neq -2, x \neq 3.

Express your answer in the form lnf(x)+c\ln|f(x)| + c.

Reveal Answer

4x17x2x6=A(x+2)+B(x3)\frac{4x - 17}{x^2 - x - 6} = \frac{A}{(x + 2)} + \frac{B}{(x - 3)}
=A(x3)+B(x+2)(x+2)(x3)= \frac{A(x - 3) + B(x + 2)}{(x + 2)(x - 3)}
x=3:5=5BB=1x = 3: -5 = 5B \Rightarrow B = -1
x=2:25=5AA=5x = -2: -25 = -5A \Rightarrow A = 5
4x17x2x6dx=(5(x+2)+1(x3))dx\int \frac{4x - 17}{x^2 - x - 6} dx = \int (\frac{5}{(x + 2)} + \frac{-1}{(x - 3)}) dx
=5lnx+2lnx3= 5\ln|x + 2| - \ln|x - 3|
=lnx+25lnx3= \ln|x + 2|^5 - \ln|x - 3|
=ln(x+2)5x3+c= \ln \left| \frac{(x + 2)^5}{x - 3} \right| + c

Marking Criteria
DescriptorMarks

correctly factorises the denominator to establish the form of the partial fraction decomposition

1

determines values of A and B

1

determines indefinite integral of the fraction

1

determines expression in the form lnf(x)\ln|f(x)|

1
Q3
2024
VCAA
Paper 2
1 mark
Q3
1 mark

The graph of f(x)=xh(x+1)(x4)f(x) = \frac{x - h}{(x + 1)(x - 4)}, where hRh \in R, will have no turning points when

A

h<1h < -1 and h>4h > 4

B

4<h<1-4 < h < 1

C

1h4-1 \le h \le 4

D

4h1-4 \le h \le 1

Reveal Answer
A

h<1h < -1 and h>4h > 4

This range makes the discriminant of the derivative's numerator positive, which would result in the derivative changing signs and the function having turning points.

B

4<h<1-4 < h < 1

This results from incorrectly factoring the discriminant inequality h23h40h^2 - 3h - 4 \le 0 as (h+4)(h1)<0(h+4)(h-1) < 0 instead of (h4)(h+1)0(h-4)(h+1) \le 0.

C

1h4-1 \le h \le 4

Correct Answer

Setting the derivative f(x)=0f'(x) = 0 yields a quadratic numerator x2+2hx3h4-x^2 + 2hx - 3h - 4. For no turning points, its discriminant must be 0\le 0, which simplifies to h23h40h^2 - 3h - 4 \le 0, giving 1h4-1 \le h \le 4.

D

4h1-4 \le h \le 1

This results from incorrectly factoring the discriminant inequality h23h40h^2 - 3h - 4 \le 0 as (h+4)(h1)0(h+4)(h-1) \le 0.

Q3
2025
SCSA
Paper 1
6 marks
Q3
6 marks

Determine x+6x2+2xdx\int \frac{x+6}{x^2+2x} \, dx.

Reveal Answer

Using the method of partial fractions:

x+6x(x+2)=ax+bx+2=a(x+2)+bxx(x+2)=(a+b)x+2ax(x+2)...(1)\begin{align*} \frac{x+6}{x(x+2)} &= \frac{a}{x} + \frac{b}{x+2}\\ &= \frac{a(x+2)+bx}{x(x+2)} = \frac{(a+b)x + 2a}{x(x+2)} \quad ... (1) \end{align*}

Equating coefficients: a+b=1a+b=1 and 2a=62a=6
Solving gives a=3,b=2a=3, b=-2

x+6x2+2xdx=(3x2x+2)dx=3lnx2lnx+2+c\begin{align*} \therefore \int \frac{x+6}{x^2+2x} dx &= \int \left(\frac{3}{x} - \frac{2}{x+2}\right) dx\\ &= 3\ln|x| - 2\ln|x+2| + c \end{align*}
Marking Criteria
DescriptorMarks

factorises the denominator correctly

1

forms the numerator correctly using partial fractions (statement 1)

1

solves correctly for aa and bb

1

re-writes the integrand in terms of the partial fractions correctly

1

anti-differentiates the reciprocal terms correctly using the absolute value

1

uses a constant of integration

1
Q1
2020
QCAA
Paper 1
1 mark
Q1
1 mark

The indefinite integral 3x41x2dx\int \frac{3x-4}{1-x^2} dx can be determined using the partial fractions 11+x+21x\frac{-1}{1+x} + \frac{2}{1-x}

The value of AA is

A

3-3

B

1-1

C

11

D

33

Reveal Answer
A

3-3

This value is incorrect. Based on the provided partial fractions, the numerator for the term with denominator 1+x1+x is 1-1, not 3-3.

B

1-1

Correct Answer

The problem provides the partial fraction decomposition 11+x+21x\frac{-1}{1+x} + \frac{2}{1-x}. By comparing this to the standard form A1+x+B1x\frac{A}{1+x} + \frac{B}{1-x}, we can identify that AA corresponds to the numerator of the first term, which is 1-1.

C

11

This value has the wrong sign. The numerator given in the partial fraction decomposition is 1-1.

D

33

This value is incorrect. It does not match the numerator 1-1 found in the term 11+x\frac{-1}{1+x}.

Q4
2022
SCSA
Paper 1
8 marks
Q4a
3 marks

Function f(x)=5(x+1)(x1)(x2+3x+1)f(x) = \frac{5(x + 1)}{(x - 1)(x^2 + 3x + 1)} can be expressed in the form ax1+bx+cx2+3x+1\frac{a}{x - 1} + \frac{bx + c}{x^2 + 3x + 1}.

Determine the value of the constants aa, bb and cc.

Reveal Answer

5x+5(x1)(x2+3x+1)=a(x2+3x+1)+(x1)(bx+c)(x1)(x2+3x+1)=(a+b)x2+(3ab+c)x+(ac)(x1)(x2+3x+1)\begin{aligned} \frac{5x+5}{(x-1)(x^2+3x+1)} &= \frac{a(x^2+3x+1) + (x-1)(bx+c)}{(x-1)(x^2+3x+1)} \\ &= \frac{(a+b)x^2 + (3a-b+c)x + (a-c)}{(x-1)(x^2+3x+1)} \end{aligned}

Equating coefficients:

a+b=03ab+c=5ac=5\begin{align*} a+b &= 0\\ 3a-b+c &= 5\\ a-c &= 5 \end{align*}

Solving gives a=2a=2, b=2b=-2, c=3c=-3

i.e. 5(x+1)(x1)(x2+3x+1)=2x1(2x+3)x2+3x+1\begin{align*} \text{i.e. }\frac{5(x+1)}{(x-1)(x^2+3x+1)} = \frac{2}{x-1} - \frac{(2x+3)}{x^2+3x+1} \end{align*}
Marking Criteria
DescriptorMarks

forms the correct expression for the equivalent numerator

1

equates coefficients correctly to form 3 linear equations

1

solves correctly to determine aa, bb and cc

1
Q4b
5 marks

Hence determine 10x+10(x1)(x2+3x+1)dx\int \frac{10x + 10}{(x - 1)(x^2 + 3x + 1)} \, dx.

Reveal Answer

10x+10(x1)(x2+3x+1)dx=25x+5(x1)(x2+3x+1)dx=4x12(2x+3)x2+3x+1dx=4lnx12lnx2+3x+1+k=ln((x1)4(x2+3x+1)2)+k\begin{aligned} \int \frac{10x+10}{(x-1)(x^2+3x+1)} dx &= 2 \int \frac{5x+5}{(x-1)(x^2+3x+1)} dx \\ &= \int \frac{4}{x-1} - \frac{2(2x+3)}{x^2+3x+1} dx \\ &= 4\ln|x-1| - 2\ln|x^2+3x+1| + k \\ &= \ln\left( \frac{(x-1)^4}{(x^2+3x+1)^2} \right) + k \end{aligned}
Marking Criteria
DescriptorMarks

expresses the given integrand as double f(x)f(x)

1

writes the integrand correctly in terms of the partial fractions

1

anti-differentiates ax1\frac{a}{x-1} correctly using the absolute value of a natural logarithm

1

anti-differentiates bx+cx2+3x+1\frac{bx+c}{x^2+3x+1} correctly

1

uses a constant of integration

1
Q4
2024
SCSA
Paper 1
6 marks
Q4a
2 marks

Given that ax+1+b(x+1)2=5x+3(x+1)2\frac{a}{x + 1} + \frac{b}{(x + 1)^2} = \frac{5x + 3}{(x + 1)^2}, determine the values for aa and bb.

Reveal Answer

ax+1+b(x+1)2=a(x+1)+b(x+1)2=ax+(a+b)(x+1)2\frac{a}{x+1} + \frac{b}{(x+1)^2} = \frac{a(x+1)+b}{(x+1)^2} = \frac{ax+(a+b)}{(x+1)^2}
Equating coefficients:
a+b=3a+b = 3
a=5a = 5
b=2b = -2
Solving gives a=5, b=2a = 5, \ b = -2

Marking Criteria
DescriptorMarks

forms the equivalence of numerators correctly

1

solves for a,ba, b correctly

1
Q4b
4 marks

Hence determine 5x+3(x+1)2dx\int \frac{5x + 3}{(x + 1)^2} \, dx.

Reveal Answer

5x+3(x+1)2dx=5x+12(x+1)2dx=5lnx+1+2x+1+k\begin{align*} \int \frac{5x+3}{(x+1)^2} \, dx &= \int \frac{5}{x+1} - \frac{2}{(x+1)^2} \, dx\\ &= 5\ln|x+1| + \frac{2}{x+1} + k \end{align*}
Marking Criteria
DescriptorMarks

re-writes the integrand correctly in terms of the partial fractions

1

anti-differentiates the (x+1)1(x+1)^{-1} term correctly using the absolute value of a natural logarithm

1

anti-differentiates the 2(x+1)22(x+1)^{-2} term correctly

1

uses a constant of integration

1
Q13
2022
QCAA
Paper 1
6 marks
Q13a
4 marks

Use partial fractions to determine 22(2x3)(x+4)dx\int \frac{22}{(2x-3)(x+4)} dx

Reveal Answer

22(2x3)(x+4)=A2x3+Bx+4\frac{22}{(2x-3)(x+4)} = \frac{A}{2x-3} + \frac{B}{x+4}
22=A(x+4)+B(2x3)\therefore 22 = A(x+4) + B(2x-3)
Let x=32:A(32+4)=22A=4x = \frac{3}{2}: A(\frac{3}{2}+4) = 22 \Rightarrow A = 4
Let x=4:B(2×43)=22B=2x = -4: B(2 \times -4 - 3) = 22 \Rightarrow B = -2
222x2+5x12dx=42x3dx+2x+4dx\int \frac{22}{2x^2+5x-12} dx = \int \frac{4}{2x-3} dx + \int \frac{-2}{x+4} dx
=222x3dx21x+4dx= 2 \int \frac{2}{2x-3} dx - 2 \int \frac{1}{x+4} dx
=2ln2x32lnx+4+c= 2 \ln|2x-3| - 2 \ln|x+4| + c

Marking Criteria
DescriptorMarks

correctly sets up the partial fractions

1

determines value of A

1

determines value of B

1

determines an expression for the indefinite integral

1
Q13b
2 marks

Use the result from Question 13a) to determine 3022(2x3)(x+4)dx\int_{-3}^{0} \frac{22}{(2x-3)(x+4)} dx
Express your answer in simplest form.

Reveal Answer

3022(2x3)(x+4)dx\int_{-3}^{0} \frac{22}{(2x-3)(x+4)} dx
=[2ln2x32lnx+4]30= [2 \ln|2x-3| - 2 \ln|x+4|]_{-3}^{0}
=((2ln32ln4)(2ln92ln1))= ((2 \ln|-3| - 2 \ln|4|) - (2 \ln|-9| - 2 \ln|1|))
=2(ln(3)ln(4)ln(9))=2ln(39×4)= 2(\ln(3) - \ln(4) - \ln(9)) = 2 \ln(\frac{3}{9 \times 4})
=2ln(112)= 2 \ln(\frac{1}{12})

Marking Criteria
DescriptorMarks

substitutes limits of integration into the result from 13a)

1

expresses a definite integral value in simplest form

1
Q5
2021
SCSA
Paper 1
5 marks
Q5a
2 marks

Given that 7x212x+2(x2)(x2+2)=ax2+bxx2+2\frac{7x^2 - 12x + 2}{(x - 2)(x^2 + 2)} = \frac{a}{x - 2} + \frac{bx}{x^2 + 2} determine the values of aa and bb.

Reveal Answer

ax2+bxx2+2=a(x2+2)+bx(x2)(x2)(x2+2)=(a+b)x22bx+2a(x2)(x2+2)\begin{align*} \frac{a}{x-2} + \frac{bx}{x^2+2} = \frac{a(x^2+2)+bx(x-2)}{(x-2)(x^2+2)} = \frac{(a+b)x^2-2bx+2a}{(x-2)(x^2+2)} \end{align*}

Equating coefficients: a+b=7a+b=7, 2b=12-2b=-12, and 2a=22a=2

Solving gives a=1, b=6a=1, \ b=6

Marking Criteria
DescriptorMarks

forms the equivalence of numerators correctly

1

solves for a,ba,b correctly

1
Q5b
3 marks

Hence determine 7x212x+2(x2)(x2+2)dx\int \frac{7x^2 - 12x + 2}{(x - 2)(x^2 + 2)} \, dx.

Reveal Answer

7x212x+2(x2)(x2+2)dx=(1x2+6xx2+2)dx=1x2dx+32xx2+2dx=lnx2+3ln(x2+2)+k\begin{align*} \int \frac{7x^2-12x+2}{(x-2)(x^2+2)} \, dx &= \int \left( \frac{1}{x-2} + \frac{6x}{x^2+2} \right) dx\\ &= \int \frac{1}{x-2} \, dx + 3 \int \frac{2x}{x^2+2} \, dx\\ &= \ln|x-2| + 3\ln(x^2+2) + k \end{align*}
Marking Criteria
DescriptorMarks

re-writes the integrand correctly in terms of the partial fractions

1

anti-differentiates the (x2)1(x-2)^{-1} term correctly using the absolute value of a natural logarithm AND uses an integration constant

1

anti-differentiates the 6x(x2+2)16x(x^2+2)^{-1} term correctly (absolute value not required)

1
Q3
2023
VCAA
Paper 1
3 marks
Q3

A particle moves along a straight line. When the particle is xx m from a fixed point OO, its velocity, vv m s1^{-1}, is given by

v=3x+22x1, where x1.v = \frac{3x + 2}{2x - 1}\text{, where } x \ge 1.

Q3a
2 marks

Find the acceleration of the particle, in m s2^{-2}, when x=2x = 2.

Reveal Answer

a=vdvdx=3x+22x1×7(2x1)2a = v\frac{dv}{dx} = \frac{3x+2}{2x-1} \times \frac{-7}{(2x-1)^2}

When x=2x=2, a=5627a = -\frac{56}{27}.

Marking Criteria
DescriptorMarks

Correctly differentiates vv with respect to xx to find dvdx\frac{dv}{dx}, or sets up a correct expression for acceleration such as vdvdxv\frac{dv}{dx} or ddx(12v2)\frac{d}{dx}\left(\frac{1}{2}v^2\right)

1

Correctly calculates the final acceleration when x=2x=2 as 5627-\frac{56}{27}

1
Q3b
1 mark

Find the value that the velocity of the particle approaches as xx becomes very large.

Reveal Answer

32\frac{3}{2}

Marking Criteria
DescriptorMarks

States the correct limiting value of 32\frac{3}{2}

1

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