MSIN0180 - Quantitative Methods for Business 2020/21
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MSIN0180 Quantitative Methods for Business
Main Summer Assessment
2020/21
1. This is a question on the solution of linear equations and vector spaces
a. Consider the system of linear equations
x + y + az = 1 、
x + ay + z = b .
x _ y + 3z = 1 .
where a; b are real numbers. Giving your reasoning, Önd the values of a and b such that the system has
i. exactly one solution,
ii. more than one solution,
iii. no solutions.
[10 Marks]
b. Consider the set of 4 vectors in R4 ; v1 = (1; 1; 1; 0); v2 = (1; _1; 0; _1); v3 = (1; 1; 0; 3); v4 = (1; _1; 1; k) : For what value of k does this form a linearly dependent set?
[10 Marks]
2. This is a question on di§erentiation and applications
a. Find the equation of the normal to the tangent line to the graph of 3x2 _ 7y2 + 4xy _ 8x = 0
at the point P (_1; 1) ; giving the equation in the form ay + bx + c = 0: [5 Marks]
b. Express the function
2x2
f (x) =
in partial fractions. Hence, Önd the value when x = 1: [6 Marks]
c. Sketch the graph of
y = x3 + 2x2 _ x _ 2;
showing clearly turning points and intercepts on both axes. [9 Marks]
3. This question is on di§erential equations
a. Find the general solution of the following second order di§erential equation y\\ + 3y + 2y\ = 4e字x + 2sin x:
[10 Marks]
b. Find the general solution of the di§erential equation
dy 1
dx 2
Hint: You may use the following result in your integration working
sin(A + B) + sin(A _ B)
2
[10 Marks]
4. DeÖne the deÖnite integrals In (x) for n e Zf by
In (x) 三
1
xn ^1 _ xdx:
d
Use integration by parts to derive the recursion formula
In (x) = aIn-1 (x) n > 1:
where a should be stated. [16 Marks]
Hence evaluate I4 (x) : [4 Marks]
5. This question is on limits
a. Using the expansion of sin(kx) when x is small, show that
x-(li)m二d ╱ 、 = ╱a3 _ 83、
[10 Marks]
Use the fact that if
lim log f (x) _二 l;
x-二a
then
lim el。g f {x3 _二 el
x-二a
lim (sinx)tan x
x-二T/3
[10 Marks]
2023-04-15