MATH2069 Mathematics 2A Final Exam Term Three 2021
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Final Exam Term Three 2021
MATH2069
Mathematics 2A
Submit solutions to this question at the Q1 submission link
1. [20 marks]
i) [5 marks] Consider a particle traveling in R3 along the curve with parametric equations
x(t) = te-3t, y(t) = 3te-2t, z(t) = 2te-2t, t e [0, 1].
a) Find the point P at which the velocity of the particle is parallel to the vector i.
b) Find the equation of the plane orthogonal to the curve at P .
ii) [5 marks] The point (0, 0) is a critical point of the function f (x, y) = 2ax2 + (a _ 1)y2 ,
for every real value a.
a) Find the values of the parameter a such that f has a saddle point at (0, 0).
b) Find the values of the parameter a such that f has a local minimum at (0, 0).
c) Find the values of the parameter a such that f has a local maximum at (0, 0).
iii) [5 marks] Let f (x, y) = x4 + y4 + 2y2 _ 2.
a) Find the maximum directional derivative of f at (1, 1).
b) Find the direction v = (a, b) so that the directional derivative of f along v at (1, 1) is zero, namely Dv f (1, 1) = 0.
iv) [5 marks] You are given the sets
A = {(x, y) e R2 : x2 + (y _ 1)2 < 1}
and
B = {(x, y) e R2 : x2 + y2 < 1}.
a) Sketch the set S given by the intersection of sets A and B .
b) Set up a double integral that represents the area of S . (DO NOT COMPUTE THE INTEGRAL.)
Submit solutions to this question at the Q2 submission link
2. [20 marks]
i) [6 marks] Let
a) Sketch D1 and D2 on separate Argand diagrams and for each set state if it is a domain. Explain your answer.
b) Find and sketch the image of D1 under the mapping w = z2 .
c) Find and sketch the image of D2 under the mapping w = 1
ii) [3 marks]
a) Express log(1 _ ^3i) in Cartesian form.
b) Hence find Log(1 _ ^3i) in Cartesian form.
iii) [7 marks] Suppose that
f (z) =
3 + 2i |
(z _ 3)(z + 2i) . |
a) Sketch and write down the three (maximal) regions with centre at z = 2 on which f (z) has a convergent Laurent (or Taylor) expansion in powers of z _ 2.
b) Find the Laurent series expansion of f in powers of z _ 2, which is convergent at the point z = 0.
iv) [4 marks]
a) Let γ be the arc of the circle of radius 2, centred at the origin, that goes from 2 to 2i, in the anticlockwise direction. Evaluate y |z|2 dz and express the result in Cartesian form.
b) Let Γ be any contour from _i to 2i that does not cross the negative real axis nor the origin. Using the fundamental theorem of contour
integration, evaluate 1 dz and express the result in Cartesian form.
Submit solutions to this question at the Q3 submission link
3. [20 marks]
i) [5 marks] Use the change of variables
x = r cos θ y = sin θ
to compute the double integral
I = ╱x2 + 1、dx dy,
l
where d is the part of the ellipse {(x, y) e R2 : x2 + 4y2 < 1} contained in the first quadrant.
ii) [4 marks] Let V be the region inside the cylinder of equation x2 +y2 = 1, between the paraboloid z = x2 + y2 and the plane z = 4.
a) Express V in cylindrical coordinates.
b) Set up the integral that represents the volume of V in cylindrical coordinates.
c) Compute the volume of V .
iii) [5 marks] Let S be the section of the spherical surface x2 + y2 + z2 = 2
for which z > 1
a) Sketch S .
b) In the y-z plane, sketch the section of S for which x = 0. The line z = intersects the circle y2 + z2 = 2 at a point P on the right side of the y-z plane. Find the cosine of the angle between the z-axis and
_→
the vector OP .
c) Parametrise S using spherical coordinates and write down the inte- gral that gives the area of S .
(DO NOT COMPUTE THIS INTEGRAL.)
iv) [6 marks]
Consider the vector field F = z i + x j + y k and the surface S given by x2 + y2 + z2 = 4.
a) Calculate the curl of F.
b) Consider the curve of intersection √ of the surface S and the plane y = 0. Use Stokes Theorem to calculate F . dr where √ is positively
C
oriented.
c) Consider the curve of intersection √ of the surface S and a plane through the origin given by ax + by +cz = 0. Determine an equation
for the plane through the origin which MAXIMISES the flow integral F . dr.
C
Submit solutions to this question at the Q4 submission link
4. [20 marks]
i) [6 marks] You are given the function v : R2 → R defined by v(x, y) = cos x sinh y + 6x2y _ 2y3 .
a) Show that v is harmonic.
b) Find u such that f (x + iy) = u(x, y) + iv(x, y) is analytic for all x, y e R.
ii) [7 marks] Suppose that
a) Find and classify all singularities of f , justifying your answers. π
2
c) Hence, or otherwise, calculate the integral
f (z)dz,
Γ
where Γ denotes the circle with centre at 1 and radius 3, traversed in the anticlockwise direction.
iii) [7 marks] Use complex analysis methods to find
c sin x
-c (x2 + 2x + 2)
2022-11-23