MATH1131 MATHEMATICS 1A Semester 2 2017
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Semester 2 2017
MATH1131
MATHEMATICS 1A
1. i) Determine the value of each of the following limits or explain why the limit does not exist.
7x2 + 5
x→o 16x2 + 13x − 2
x2017
|x2 − 1|
x→ 1 x − 1
d) x(l) ╱ 1 + 、2x
ii) Find all values a and b (if any) such that the function f : 重 → 重 defined by
f (x) = 0(0) .
is both continuous and differentiable at 0.
iii) Let y = xsin x. Find dy
iv) Evaluate the following integrals.
a) I1 = )1 2 xe2xdx
b) I2 = ) dx
v) Show that the
ex + 1 = 5 cos x
has at least one positive solution.
2. i) Let
y = )0 sin x dt.
dy
a) Find
b) Find all stationary points for y on the interval (0, π).
c) For each stationary point, determine whether it is a local maximum, a local minimum, or neither.
ii) A lighthouse with a rotating beacon is located in the ocean 2 kilometers from the shore. The beacon rotates at a constant rate of 5 revolutions per minute. Assume the shoreline is straight, and let P be the point on the coastline which is closest to the lighthouse. At any time t, let X be the point where the beacon’s beam of light hits the shoreline, and x the distance from X to P . How fast is x changing when X is 3 kilometers away from P?
iii) Determine which, if any, of the following improper integrals converge Give reasons for your answers.
a) )2 o dx,
b) )1 o dx.
iv) a) Show that
cosh x + sinh x = ex .
b) Show that
(cosh x + sinh x)3 = cosh(3x) + sinh(3x).
v) Consider the polar curve
r = 4 − sin θ.
a) Find all points at which the tangent is horizontal or vertical.
b) Show that the curve is symmetric under reflection in the y-axis.
c) Sketch the curve.
3. i) Let z = α + 2i and w = 2 − 3i, where α is a real number.
b) Calculate w , expressing your answer in Cartesian form a + ib.
π ii) Let z be a complex number with |z| = 2 and Arg(z) =
a) Write down the polar form of z .
b) Hence or otherwise evaluate ╱ 1 + √3i、3001 expressing your answer in Cartesian form.
iii) a) Find all the sixth roots of unity, expressing your answers in Cartesian form.
b) Write z6 − 1 as a product of real linear and irreducible real quadratic factors.
iv) a) Use De Moivre’s theorem to write sin 3θ as a sum of powers of sin θ .
b) Hence or otherwise find one solution to the equation
4x3 − 3x + = 0.
(Your solution must be expressed exactly, and not in decimal form).
v) The system of linear equations
x + y − z = 0
2x + y + 2z = 0
has infinitely many solutions.
a) Use Gaussian elimination to find the general solution to the system in terms of a parameter.
b) Hence, or otherwise, write down the point normal form of the plane with parametric vector equation
x = │(╱)丫(、) + λ │(╱)1丫(、) + µ │(╱)丫(、) .
4. i) Sketch the following region S on the Argand diagram:
S = (z ∈ d : Im(z) ≤ 1 and − ≤ Arg(z) ≤ ).
ii) Consider the matrix
A = ╱ 0(1) │ − √3
0
√2
0
0(√)3、
− 1丫 .
a) Find det(A).
b) Use the following Maple output to help you answer the question below.
A q :> <<全,à,tqsI人3)A|<à,tqsI人A),àA|<–tqsI人3),à,–全AA;
A := ╱ 0(1)
│ − √3
0
√2
0
0(√)3、
− 1丫
A qr5/4;
╱ 0(1) │ − √3
0
√2
0
0(√)3、
− 1丫
α) [2 marks] Show that A4 = 4I, giving reasons.
β) [1 mark] Hence express A_1 as a scalar multiple of A3 .
iii) Let
P = ╱ 2(1) │2
− 1
1
0
3、
4 丫 ,
Q = ╱3(2) 0(1) 、
│ 1 − 1丫 .
a) Find QT P .
b) Write down a 3 × 3 matrix D such that the rows of DP are 2r1 , r2 and −r3 , where r1 , r2 , r3 are the rows of P .
iv) Find the shortest distance between the point P with position vector p = │(╱) 丫(、) and the plane
x + 2y + 3z = 5.
╱b1 、
v) Let α be a real parameter and b = be a vector in 重4 . Consider
│b4 丫
the following system of linear equations in x1 , x2 , x3 , x4 .
a) Find all possible values of α such that the system has a unique solu- tion for all choices of b.
b) Find conditions on b that ensure the system has a solution for all choices of α .
vi) Given that P and Q are invertible n × n matrices and that Q is symmetric, simplify (PT Q)T (QP)_1 .
2022-04-28