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Semester 2 Assessment, 2019
School Mathematics and Statistics
MAST10005 Calculus 1
Writing time: 3 hours
Reading time: 15 minutes
This is NOT an open book exam
This paper consists of 6 pages (including this page)
Authorised Materials
• Mobile phones, smart watches and internet or communication devices are forbidden.
• Calculators, tablet devices or computers must not be used.
• No handwritten or print materials may be brought into the exam venue.
Instructions to Students
• You must NOT remove this question paper at the conclusion of the examination.
• All questions may be attempted. All answers should be appropriately justified.
• Number the questions and question parts clearly. Start each question on a new page.
• Use the left pages for rough working. Write material that you wish to be marked on the
right pages only.
• A limited formula sheet is provided on the back of this cover page. You may remove this
cover page in order to use the formula sheet if you wish.
• This exam paper consists of 6 pages in total and there are 12 questions.
• There are 12 questions with marks as shown. The total number of marks available is 109.
Instructions to Invigilators
• Students must NOT remove this question paper at the conclusion of the examination.
• Each candidate should be issued with an examination booklet, and with further booklets
as needed.
This paper may be held in the Baillieu Library
MAST10005 Semester 2, 2019
Useful Formulae
Pythagorean identity
cos2(x) + sin2(x) = 1
Compound angle formulae
sin(x+ y) = sin(x) cos(y) + cos(x) sin(y)
cos(x+ y) = cos(x) cos(y)− sin(x) sin(y)
tan(x+ y) =
tan(x) + tan(y)
1− tan(x) tan(y)
Derivatives of inverse trigonometric functions
arcsin′(x) =
1√
1− x2
arccos′(x) = − 1√
1− x2
arctan′(x) =
1
1 + x2
Antiderivatives from inverse trigonometric functions∫
1√
s2 − x2 dx = arcsin
(x
s
)
+ C∫ −1√
s2 − x2 dx = arccos
(x
s
)
+ C∫
1
s2 + x2
dx =
1
s
arctan
(x
s
)
+ C
where s is a positive constant, and C is an arbitrary constant of integration.
Complex exponential formulae
eiθ = cos(θ) + i sin(θ)
cos(θ) =
1
2
(
eiθ + e−iθ
)
sin(θ) =
1
2i
(
eiθ − e−iθ)
Vector projections
• The vector projection of v onto u is v‖ = (uˆ · v)uˆ = ku, where k ∈ R is the unique solution
of u · (v − ku) = 0.
• The vector component of v perpendicular to u is v⊥ = v − v‖.
Complex roots
The n-th roots of w = seiφ are s
1
n ei(
1
n
(φ+2kpi)) for k = 0, 1, . . . , n− 1.
Changes in speed
Provided r′(t) 6= 0, the speed function ‖r′(t)‖ is decreasing when r′(t) · r′′(t) < 0 and
increasing when r′(t) · r′′(t) > 0.
Page 2 of 6 pages
MAST10005 Semester 2, 2019
Two properties of complex numbers
(I) |zw| = |z||w| (II) zz¯ = |z|2
Question 1 (9 marks) Let
A = {z ∈ C : zz¯ < |z|}, B = {z ∈ C : |z − iz| <
√
2}.
(a) Prove that |z − iz| = √2 |z| for every z ∈ C.
(b) Prove carefully that A ⊆ B. You may use the result of (a).
(c) Is B ⊆ A? If your answer is yes, prove it. If your answer is no, give a counterexample.
(d) Express the set
D =
{
x ∈ R
∣∣∣∣ 1− xx2 + x+ 1 < 2
}
as a union of intervals.
Question 2 (7 marks)
(a) Evaluate the following in Cartesian form x+ iy where x and y are real:
(i)
(6− 2i)(4− 7i)
2− i
(ii)
(−
√
3 + i)6
(b) Find the following real numbers:
(i)
Arg
(
−
√
3 + i
)
(ii) ∣∣∣∣(6− i)2(4− 3i)1 + 6i
∣∣∣∣
Question 3 (7 marks)
(a) Sketch the set A = {z ∈ C | Arg(z) ∈ (pi4 , 3pi4 ]}.
(b) Multiply a general z = reiθ ∈ C by i = ei pi2 . Hence describe the geometric effect of
multiplying a complex number by i.
(c) Use your answers to (a) and (b) to sketch the set B = {w ∈ C | iw ∈ A} (on a new
diagram).
Page 3 of 6 pages
MAST10005 Semester 2, 2019
Question 4 (8 marks)
(a) Find the set of solutions of
z6 = 32(1− i
√
3)
Express your answers in exponential polar form.
(b) Find the set S = {z ∈ C | z4 + 5z2 + 4 = 0}. Express your answers in Cartesian form.
(c) Use your answer to (b) express P (z) = z4 + 5z2 + 4 as product of two quadratic factors
with real coefficients.
Question 5 (7 marks) Consider the function
f(x) = arcsin(arccos(x))
(a) Find the implied domain of f . You will need to express your answer in terms of cosine.
(b) Find the implied range of f .
Question 6 (7 marks)
(a) Find the angle θ between u = (
√
3, 0, 0) and v = (1, 0,
√
3).
(b) For A = (1, 1, 1), B = (3, 3,−1) and Q = (3,−1,−1):
(i) Find the point P on the line L passing through A and B that is closest to Q.
(ii) Find the distance from Q to the line L.
Question 7 (12 marks) Consider the curve
C = {(x, y) ∈ R2 | x2 − xy + 2y2 = 7}
(a) Find all intercepts of C.
(b) Use implicit differentiation to find a formula for dydx in terms of x, y.
(c) Find any points in C where the tangent line is horizontal.
(d) Find any points in C where the tangent line is vertical.
(e) Use (a) to (d) to sketch C.
Page 4 of 6 pages
MAST10005 Semester 2, 2019
Question 8 (8 marks) The function r : R −→ R2 defined by
r(t) = et cos(t)i+ et sin(t)j
is a type of parametric curve known as a logarithmic spiral.
(a) Calculate the velocity r′(t) at time t.
(b) Calculate the speed ‖r′(t)‖ at time t.
(c) Calculate the acceleration r′′(t) at time t.
(d) Find the cosine of the angle θ between r(t) and r′(t) at time t and hence find the angle
between r(t) and r′(t).
(e) Calculate r′(t) · r′′(t) and hence explain why the speed is always increasing.
Question 9 (13 marks) Consider the function given by formula
f(x) = 2x
√
1− x2
(a) Find the implied domain of f .
(b) Find the x and y intercepts of f . Express your answer as a set.
(c) Find the stationary points of f . Express your answer as a set.
(d) Find the intervals on which f is concave up and the intervals on which f is concave down.
(e) Find the inflection points of f . Express your answer as a set.
(f) What does the answer to (d) tell us about the stationary points found in (c)?
(g) Use the answers to previous parts of this question to sketch the graph of f .
Question 10 (9 marks)
(a) Verify that −e−x(x+ 1) is an antiderivative of f(x) = xe−x.
(b) Use integration by substitution and your answer to (a) to evaluate∫ pi
2
0
sin(x)e− sin(x) cos(x) dx.
It may help to express the integrand in terms of f(x) aa defined in (a). Explain carefully
which rules of integration you use.
(c) Evaluate the integral ∫ e√pi
1
sin(log2(x)) log(x)
x
dx.
Explain carefully which rules of integration you use.
(d) Find the area enclosed between the curves y = sin(x), y = cos(x) and the and the hori-
zontal axis on [0, pi]. A sketch is always helpful.
Page 5 of 6 pages
MAST10005 Semester 2, 2019
Question 11 (11 marks) Evaluate the following antiderivatives.
(a)
∫
(2x− 3)2(x+ 2) 32 dx. [Hint: A linear substitution will work here.]
(b)
∫
1
4x2 + 8x+ 5
dx.
(c)
∫
cos2(x) sin5(x) dx.
Question 12 (11 marks) Consider the initial value problem
dy
dx
= (y2 − 1) cos(x), y = 0 when x = 0.
(a) What are the constant solutions of the differential equation?
(b) Explain briefly why the range of the solution of the initial value problem is a subset of
(−1, 1).
(c) Use partial fractions to express
1
y2 − 1 as a sum of two fractions with linear denominators.
(d) Find a formula for y by solving the initial value problem. You will need to use your answer
to (c). The result from (b) will allow you to remove all absolute value signs when solving
to find a formula for y. You may use this even if you haven’t completed part (b).
End of Exam—Total Available Marks = 109