Chapter 2 M 1
Chapter 2 M 1
Chapter 2 M 1
Chapter No.: 2
Class: BSc
Subject: Mathematics-1
E-Mail: waseem.mustafa.ibd@gmail.com
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Important Points:
2.1) Introduction: This chapter discusses some of the very basic aspects of the subject,
aspects on which the rest of the subject builds. It is essential to have a firm understanding
of these topics before the more advanced topics can be understood.
2.2) Powers: When n is a positive integer, the n’th power of the number a, 𝒂𝒏 , is simply the
product of n copies of a, that is,
𝒂𝒏 = 𝒂 × 𝒂 × 𝒂 × … × 𝒂 (n times)
The number n is called the power, exponent or index. We have the power rules (or rules
of exponents) as follows:
Law Example
x1 = x 61 = 6
x0 = 1 70 = 1
2.3) Simple Algebra: Algebra is the branch of mathematics that uses letters in place of some
unknown numbers. In this course we have to learn collecting up terms, multiplication of
variables, and expansion of bracketed terms.
There are three important algebraic identities which you should know, these are as
follows:
i) (𝒂 + 𝒃)𝟐 = 𝒂𝟐 + 𝟐𝒂𝒃 + 𝒃𝟐
ii) (𝒂 − 𝒃)𝟐 = 𝒂𝟐 − 𝟐𝒂𝒃 + 𝒃𝟐
iii) 𝒂𝟐 − 𝒃𝟐 = (𝒂 + 𝒃)(𝒂 − 𝒃)
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−𝒃 ± √𝒃𝟐 − 𝟒𝒂𝒄
𝒙=
𝟐𝒂
Where; a = Coefficient of 𝒙𝟐 ,
b = Coefficient of 𝒙, and
c = Constant Term
Note: We can apply this formula even if factorization is possible
2.9) The Natural Logarithm: Formally, the natural logarithm of a positive number x,
denoted ln x (or, sometimes, log x), is the number y such that 𝒆𝒚 = 𝒙. In other words, the
natural logarithm function is the inverse of the exponential function 𝒆𝒙 (regarded as a
function from the set of all real numbers to the set of positive real numbers). Sometimes
ln x is called the logarithm to base 𝒆.
The reason for this is that we can, more generally, consider the inverse of the exponential-
type function 𝒂𝒙 . This inverse function is called the logarithm to base 𝒂 and we use the
notation 𝐥𝐨𝐠 𝒂 𝒙. Thus, 𝐥𝐨𝐠 𝒂 𝒙 is the answer to the question `What is the number y such
that 𝒂𝒚 = 𝒙?'.
The two most common logarithms, other than the natural logarithm, are logarithms to
base 2 and 10. For example, since 𝟐𝟑 = 𝟖, we have 𝐥𝐨𝐠 𝟐 𝟖 = 𝟑. It may seem awkward
to have to think of a logarithm as the inverse of an exponential-type function, but it is
really not that strange. Confronted with the question `What is 𝐥𝐨𝐠 𝒂 𝒙?', we simply turn it
around so that it becomes, as above, `What is the number y such that 𝒂𝒚 = 𝒙?'.
There is often some confusion caused by the notations used for logarithms. Some texts
use log to mean natural logarithm, whereas others use it to mean log10. In this guide, ln
will be used to mean natural logarithm.
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θ 0º 30 º 45 º 60 º 90 º
ratios (0 Rad.) (𝝅⁄𝟔 Rad.) (𝝅⁄𝟒 Rad.) (𝝅⁄𝟑 Rad.) (𝝅⁄𝟐 Rad.)
𝟏⁄ 𝟏⁄ √𝟑⁄ 1
Sin 0
𝟐 √𝟐 𝟐
1 √𝟑⁄ 𝟏⁄ 𝟏⁄ 0
Cos
𝟐 √𝟐 𝟐
𝟏⁄ 1 √𝟑 undefined
tan 0
√𝟑
2.14) Supply and Demand Functions: Supply and demand functions describe the relationship
between the price of a good, the quantity supplied to the market by the manufacturer, and
the amount the consumers wish to buy.
The demand function 𝒒𝑫 of the price p describes the demand quantity: 𝒒𝑫 (𝒑) is the
quantity which would be sold if the price were p.
Similarly, the supply function 𝒒𝑺 is such that 𝒒𝑺 (𝒑) is the amount supplied when the
market price is p.
In this course, the supply and demand functions will be given and we have to find
equilibrium price and quantity for which we assume 𝒒𝑫 (𝒑) = 𝒒𝑺 (𝒑) = 𝒒.and solve both
equations simultaneously and in some questions we also have to sketch their graphs,
which we’ll discuss in the following topic.
2.15) Further Applications of Functions: Suppose that the demand equation for a good is of
the form p = ax + b where x is the quantity produced. Then, at equilibrium, the quantity
x is the amount supplied and sold, and hence the total revenue TR at equilibrium is price
times quantity, which is
𝑻𝑹 = (𝒂𝒙 + 𝒃)𝒙 = 𝒂𝒙𝟐 + 𝒃𝒙;
a quadratic function which may be maximised either by completing the square, or by
using the techniques of calculus (discussed later).
Another very important function in applications is the total cost function of a firm. In the
simplest model of a cost function, a firm has a fixed cost, that remain fixed independent
of production or sales, and it has variable costs which, for the sake of simplicity, we will
assume for the moment vary proportionally with production.
That is, the variable cost is of the form Vx for some constant V, where x represents the
production level. The total cost TC is then the sum of these two: TC = F + V x. For a
limited range of x this very simplistic relationship often holds well but more complicated
models (for instance, involving quadratic and exponential functions) often occur.
Combining the total cost and revenue functions on one graph enables us to perform break-
even analysis. The break-even output is that for which total cost equals total revenue
(TR = TC). In simplified, linear, models the break-even point (should it exist) is unique.
When non-linear relationships are used, a number of break-even points are possible.
2.16) Graphs: In this section, we consider the graphs of functions. The graphing of functions
is very important in its own right, and familiarity with graphs of common functions and
the ability to produce graphs systematically is a necessary and important aspect of the
subject.
A diagram showing the relation between variable quantities, typically of two variables,
each measured along one of a pair of axes at right angles, as shown below:
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The graph of a function f (x) is the set of all points in the plane of the form (x; f(x)).
Sketches of graphs can be very useful. To sketch a graph, we start with the x-axis and
y-axis, as in Figure below:. (This figure only shows the region in which x and y are both
non-negative, but the x-axis extends to the left and the y-axis extends downwards.)
2.17) Sketch of Linear Function: The linear functions are those of the form y = mx + c and
their graphs are straight lines, with gradient, or slope, m, which cross the y-axis at the
point (0; c).
𝟏
Similarly, graph of y = is given shown on next page:
𝒙−𝟐
Exercise:
Q 1) Expand the following:
a) (2x − 3y)(x + 4y) b) (x 2 − 1)(x + 2) c) (𝑥 + 2)2 − (𝑥 − 2)2
3𝑎 10𝑐 3
d) (2x + 3) (𝑥 2 – x − 5) e) 2
× f) 𝑛2 − (𝑛 − 2)(𝑛 + 2)
5𝑐 𝑎2
d) 8x - 2 = -9 + 7x e) a + 5 = -5a + 5 f) 4m – 4 = 4m
a) 𝑥 2 − 5𝑥 = 0 b) 𝑥 2 − 4 = 0 c) 𝑥 2 + 5𝑥 + 6 = 0
d) 5x² + 6x + 1 = 0 e) 𝑥 2 − 7𝑥 + 12 = 0 f) 𝑥 2 − 3 = 2𝑥
Q 9) Solve the following equations by using any method also state if an equation has no
real roots:
a) 𝑥² − 4𝑥 − 8 = 0 b) 5x² + 2x + 1 = 0 c) 𝑥 2 + 4𝑥 + 1 = 0
g) 𝑥 4 − 5𝑥 2 + 4 = 0 h) 𝑥 4 − 10𝑥 2 + 9 = 0 i) 𝑥 6 − 7𝑥 3 − 8 = 0
12
j) 𝑥 6 + 𝑥 3 − 12 = 0 k) √𝑡 = 4 + l) √𝑡 (√𝑡 − 6) = −9
√𝑡
Q 10) Use the discriminant to determine the nature of the roots of the following
quadratic equations.
d) 𝑥 2 – 3𝑥– 5 = 0 e) 𝑥 2 + 2𝑥 + 1 = 0 f) 𝑥 2 – 3𝑥 + 4 = 0
Q 11) The following equations have the number of roots shown in brackets, Using the
discriminant, deduce the value or range of values of K.
e) 𝐾𝑥 2 − 3𝑥 + 5 = 0 (2) f) 𝑥 2 − 4𝑥 + 3𝐾 = 0 (1)
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b) 2x + 3y = 7 and 3x – 4y = 2
c) 5x + 2y = 9 and 3x +y = 8
d) y2 + (2x + 3)2 = 10 and 2x +y = 1
2 𝑥
e) y – x = 3 and − =1
𝑥 𝑦
Q 14) Suppose the demand function is q D (p) = 20 – 2p and that the supply function is
𝟐
q s (p) = p – 4. Find the equilibrium price p* and equilibrium quantity q*.
𝟑
Q 15) Find the equilibrium price and quantity of the following Demand functions and
Supply functions
a) Demand function: q + 5 p = 40
Supply function: 2q – 15 p = - 20
b) Demand function: q - 6 p = - 16
Supply function: q + 2 p = 40
c) Demand function: q = 12 p – 4
Supply function: q=8-4p
Q 16) Find the break-even points in the case where the total cost function is TC = 2 + 5x + x2
and the total revenue function is TR = 12 + 8x
Q 17) Suppose that the demand relationship for a product is 𝐩 = 𝟔⁄(𝐪 + 𝟏) and that the
supply relationship is p = q + 2. Determine the equilibrium Price and Quantity.
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Q 18) If the curve y = k x (x+2) meets the line y = x - k, find the range of values of k. State
the value of k for which the line is a tangent.
Q 20) Find the equilibrium price and quantity of the following demand and supply
functions also sketch both function on same graph.
a) Demand function: p = 4 – q – q2
Supply function: p = 1 + 4q + q2
b) Demand equation: q = 8 – p2 - 2 p
Supply equation: q = p2 + 2 p – 8
c) Demand equation: P = Q2 – 10Q + 25
Supply equation: P = Q2 + 6Q + 9
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Answers:
Q 1) a) 2x 2 + 5xy − 12y 2 b) x 3 + 2x 2 − x − 2 c) 8x
6𝑐
d) 2x3 + x2− 13x− 15 e) f) 4
𝑎
18 2𝑥 2
g) h)
49𝑚2 𝑝 𝑦2𝑧
Q 2) a) 7x + 3y b) 4l2 − 2k 3 c) 3x 3 + 2y 2
d) 5a + b√c
1 30x−43y
Q 3) a) 6 a + 8b − 8c b)
2 12a
Q 4) a) ½ b) 5 c) 1/3 d) 144
Q 5) a) 3/2 b) - 5/2 c) ½
Q 6) a) -2 b) 11 c) 3 d) -7
e) 0 f) No solution
1 7 −5
Q 7) a) -2 or b) -5 or c) 1 or
2 2 3
2 3 2 1 5 3
g) or − h) − or i) − or
3 2 3 2 2 4
Q 9) a) 2 ± 2 √3 b) No real roots c) −2 ± √3
−5 ± √33 −15 ± √165 −17 ± √449
d) e) f)
2 10 20
3 3
j) √3 , − √ 4 k) 36 l) 9
Q 10) a) 2 real and distinct roots b) 2 real and equal roots or 1 root
Q 14) p∗ = 9, q∗ = 2
Q 15) a) p = 4, q = 20 b) p = 7, q = 26
3
c) p= , q=5
4
Q 16) x = 5, OR x = -2
Q 17) p = 3, q = 1, OR p = -2, q = -4
Q 19) a) y
y=5
O x
O x=2 x
c)
y y = x+3
-3 O x
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d)
y = -3x-2 y
−𝟐⁄ O x
𝟑
-2
O 4 x
-8
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f)
y = -2x-8 y
-4 O x
-8
y
𝟐
𝒚 = 𝒙 − 𝟔𝒙 + 𝟓
O 1 5 x
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h)
y
11 𝒚 = 𝟐𝒙𝟐 − 𝟖𝒙 + 𝟏𝟏
(2, 3)
O x
𝟏 𝟏𝟕
(− 𝟐 , 𝟒
)
𝒑 = 𝟏 + 𝟒𝒒 + 𝒒𝟐
O q
(-2, -3) 𝒑 = 𝟒 − 𝒒 − 𝒒𝟐
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𝒒 = 𝒑𝟐 + 𝟐𝒑 − 𝟖
8
-4 O 2 p
-8 𝒒 = 𝟖 − 𝒑𝟐 − 𝟐𝒑
P 𝑷 = 𝑸𝟐 − 𝟏𝟎𝑸 + 𝟐𝟓
25
𝑷 = 𝑸𝟐 + 𝟔𝑸 + 𝟗
16
-3 O 1 5 Q
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Q 21)
q
40 𝒒 = 𝒑𝟐 + 𝟕𝒑 − 𝟐
−𝟕+√𝟓𝟕 −𝟏+√𝟏𝟔𝟏
O p
𝟐 𝟐
-2
𝒒 = −𝒑𝟐 − 𝒑 + 𝟒𝟎
Equilibrium Price = 3, and Equilibrium Quantity = 28
Q 22)
q
98 𝒒 = 𝟒𝒑 − 𝟐
𝟏 −𝟑+√𝟐𝟎𝟓
O p
𝟐 𝟐
-2
𝒒 = −𝟐𝒑𝟐 − 𝟔𝒑 + 𝟗𝟖
Equilibrium Price = 5, and Equilibrium Quantity = 118
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Q 23)
y 𝒚 = 𝟒𝒙𝟐 − 𝟖𝒙 − 𝟏
−𝟏+√𝟏𝟕 𝟐+√𝟓
O x
𝟒 𝟐
-1
Q 24)
y 𝒚 = 𝒙𝟐 + 𝟒𝒙 + 𝟏
O 𝟐 x
𝒚 = −𝒙𝟐 − 𝒙 + 𝟔
√𝟔𝟓−𝟓
The value of x at the point of intersection is x =
𝟒
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Q 25)
y
1 𝐲 = 𝟐𝐱 𝟐 − 𝐱 − 𝟑
-1 − 𝟏⁄𝟐 O 1 𝟑⁄ x
𝟐
𝐲 = 𝟏 + 𝐱 − 𝟐𝐱 𝟐
𝟏±√𝟏𝟕
The values of x at the points of intersection are x =
𝟒
Q 26)
y 𝐲 = 𝟐𝐱 𝟐 + 𝟑𝐱 − 𝟓
− 𝟓⁄𝟐 − 𝟏⁄𝟐 O 1 𝟐 x
𝐲 = 𝟔𝐱 + 𝟒 − 𝟒𝐱 𝟐
𝟑
The values of x at the points of intersection are x = Or x = -1
𝟐
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20
O q
24
O q
𝑎≥2
𝑎≥3
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Q 33) x = 3, OR x = -3
Q 34) x = 2, OR x = -2
𝑎≤3 𝑎=3
𝑐≥2 𝑐=2
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8/3 q(p + 3) = 8
O 4 p
-4
5/2 q(p + 4) = 10
O 5 p
-5
Q 39) (b)
c) 𝑐 ≥ 1
The End
Good Luck