MATH1131 MATHEMATICS 1A Semester 1 2017
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Semester 1 2017
MATH1131
MATHEMATICS 1A
1. i) Evaluate each limit, giving brief reasons for your answer.
2ex + cosx
x→∞ 6ex − sin x
x→0 x2 − 3x
ii) Evaluate each of the following integrals:
a) Z cos x sin5 xdx,
b) Z dx.
iii) The oor of x is denoted ⌊x⌋ and gives the greatest integer less than or equal to x. For example, ⌊3.1⌋ = 3.
Let f : R → R be de ned by
f(x) = ⌊3x − 1⌋ .
a) Write down the value of f(12).
b) By considering left and right limits, state whether or not f is con- tinuous at x = 13 .
√2 √2 .
a) Write z in polar form.
b) Find the smallest positive integer n such that zn = 1.
c) Find all possible positive integers m such that zm = 1.
v) Consider the following Maple output > with(LinearAlgebra):
> A := <<607,207,75>|<-2286,-783,-288>|<1414,483,176>>;
607 − 2286 1414
A := 207 − 783 483
> A^2;
1297 −4896 3024
− 207 783 −483
> A^3;
607 − 2286 1414
207 − 783 483
a) Find A100 .
b) Is A invertible? Give reasons for your answer.
vi) a) Express sin in terms of ei and e −i .
b) Find constants a, b and c such that
sin4 = acos4 + bcos2 + c.
c) Hence or otherwise evaluate
Z
2. i) Find the gradient dydx of the curve de ned by xy + y2 = 4 at the point where y = 1.
ii) Let f : R → R be given by f(x) = 3x − cos x.
a) Show that f has a zero in the interval 0, 2 .
b) What is the minimum value of f′ ?
c) Explain why f has an inverse on R.
d) Find the value of g′ ( − 1), where g is the inverse of f .
iii) Sketch the graph of the polar curve r = 2 − cos2 for 0 ≤ ≤ .
iv) For some values of the real parameters a, b, c and d, the curve ax2 + by2 + cx + dy = 1
passes through the points A(1, 1),B(2, 3) and C(0, 1).
a) Explain why the following equations can be used to determine the values of a, b, c and d for which the curve passes through the points.
a + b + c + d = 1
4a + 9b + 2c + 3d = 1
b + d = 1.
b) Use Gaussian Elimination to solve the system of linear equations in part (a).
c) Are there zero, one, or in ntely many curves of the form
ax2 + by2 + cx + dy = 1 which pass through the points A, B and C? d) Using your answer from part (b), nd the parabola of the form
y = x2 + x + which passes through A, B and C .
v) a) Write as a linear combination of 6 and 2 .
3. i) a) Clearly state the Mean Value Theorem.
b) Apply the Mean Value Theorem to f : R → R given by f(t) = e2t − t
x,
e2x ≥ 2x + 1.
ii) a) De ne the hyperbolic function cosh x in terms of exponentials.
b) Use the de nition to prove that
cosh2x = 2 cosh2 x − 1.
iii) Evaluate the integral xlnxdx.
iv) The point (x(t),y(t)) is moving clockwise on the circle x2 + y2 = 100.
dy x dx
dt y dt .
b) If the velocity in the x direction at x = 6 is 2 units/sec, nd the
velocity in the y direction.
v) Consider the function f de ned for all real x by f(x) = 0 x dt.
a) Find ddx f(x3 ) .
b) Explain why f is an even function.
c) By considering the improper integral, 1 ∞ dt, explain why lim f(x) exists.
x→∞
vi) The Maple output below shows a calculation and then the upper Rie- mann sum for the function f : (0, ∞ ) → R, given by f(x) = lnx, on the interval [1, 6] using the partition shown. The value of the upper Riemann sum is approximately 6.181297752.
Find, to two decimal places, the value of the corresponding lower Rie- mann sum.
> [seq(i*0.5, i = 2..12)];
[1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0] > map(ln,%);
[0., .4054651081, .6931471806, .9162907319, 1.098612289, 1.252762968,
1.386294361, 1.504077397, 1.609437912, 1.704748092, 1.791759469]
> with(Student[Calculus1]):
> RiemannSum(ln(x), x = 1..6, method = upper, output = plot);
4. i) Let a = 4(1) and b = 5(5) be two vectors in R2 .
a) Calculate projb (a).
b) Sketch the vectors a, b and projb (a) in the plane.
ii) Calculate the inverse of the matrix A =
0 0 1
iii) Let C = 4(1) 6 |
0(2) 3 |
and D = 5(0) 0(5) |
5(0) . |
a) Find DC .
b) What is the size of CD?
iv) Let u = and v = .
a) Calculate u × v .
b) Hence or otherwise nd 60(0)0
v) Let P1 and P2 be the planes in three dimensional space with Cartesian equations 12x + 9y + 3z = 75 and z = 51 − 4x − 3y respectively.
a) Explain why P1 and P2 are parallel.
b) Show that (5, 1, 2) is a point on P1 .
c) It is given that the line L with parametric vector equation
= + ; ∈ R,
passes through the point (5, 1, 2) and is perpendicular to both P1 and P2 . Determine where the line L meets the plane P2 .
d) Hence, or otherwise, nd the shortest distance between P1 and P2 .
e) Find a point Q with the property that the set of all points equidistant from (5, 1, 2) and Q is the plane P2 .
vi) Suppose that A and B are two n × n matrices and that AB − A is
invertible. Prove that BA − A is also invertible.
2022-04-28