ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
25 JUNE – 3 JULY 2018 ℝ
snash’s
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℚ
ℤ
be able to:
ℚ′
ℤ Upon completion of this chapter, readers should
ℝ
ℕℚ′ℝ ℝℂ
1. Define and state the rules of indices, surds
ℕ
ℂ
2. Perform the algebraic operations of indices,
ℂ
ℝ
ℚ′
ℚ′ ℕ
and logarithms.
ℚ
3. Solve equations involving indices, surds, logarithms and complex numbers. ℝ
snash’s
ℤ
surds, logarithms and complex numbers.
ℚ
TYPES OF NUMBER
INTERVAL OF REAL NUMBER
COMPLEX NUMBER
INDEX RULES / OPERATIONS
OPERATIONS
SURD SOLVING EQUATION
SOLVING EQUATION
snash’s
LOG
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
TYPES OF NUMBERS REAL; â„?
A number that has a decimal representation.
Examples: 1, 0.5, 2.11111 , 2/3 Number that can’t be Number that can be represented as fraction represented of two as a fraction of RATIONAL; â„š IRRATIONAL; ℚ’ đ?‘Ž integers. , and a,b ∈ đ?‘?, đ?‘? ≠0 . đ?‘? 0 & +ve integers Examples: 2.3154‌ , e,Examples: 3 -1, 35 , -ve 0.2,integers, 1. 23 Examples: ‌, -1, 0, 1, 2, ‌ INTEGER; ℤ
WHOLE;W NATURAL; ℕ snash’s
Zero and Natural numbers
Examples: 0, 1, 2, ‌ Counting numbers Example: 1,2,..
Example 1: List the numbers in the set 4 {−3, , 0, 0.12, 2, đ?œ‹, 2.1515 ‌ , đ?‘’, 10} that are 3
a) b) c) d) e) f)
snash’s
Natural numbers Whole numbers Integers Rational numbers Irrational numbers Real numbers
Example 2: Express the following decimal numbers as fractions. c) 1.651
snash’s
d) 0.725
REAL NUMBER LINE & INTERVALS
INTERVALS
OPEN
snash’s
CLOSE
HALF-OPEN/ HALF-CLOSE
INFINITE
INTERVAL
a x b
[ -2, 1]
a< x <b
(a,b) ( -2 , 1 )
a x <b
-2 x <1 a<x b
-2< x 1
x>a @ a< x< x<a @ -< x<a x > -2 @ - 2 < x <
REAL NUMBER LINE
[a,b]
-2 x 1
-2 < x <1
snash’s
SYMBOL
[a,b) [ -2 , 1 ) (a,b] ( -2 , 1 ] ( a , ) ( - , a ) ( -2 , )
TYPE
Close interval
a
b Open interval
a
a a
b b b
Half open interval Half open interval Infinite interval
Example 3: Rewrite each of the following inequalities by using interval notation and illustrate them on the real number line.
snashâ&#x20AC;&#x2122;s
a) â&#x2C6;&#x2019;3 < đ?&#x2018;Ľ < 5
b) â&#x2C6;&#x2019;1 < đ?&#x2018;Ľ â&#x2030;¤ 0
c) đ?&#x2018;Ľ â&#x2030;Ľ â&#x2C6;&#x2019;2
d) đ?&#x2018;Ľ < 0
Exercise: Example 4: Write each of the following intervals as inequalities. Use đ?&#x2018;Ľ as the variable.
snashâ&#x20AC;&#x2122;s
a) (â&#x2C6;&#x2019;â&#x2C6;&#x17E;, 5]
b) [â&#x2C6;&#x2019;2, 3]
c) [3, â&#x2C6;&#x17E;)
d) (â&#x2C6;&#x2019;1, 7)
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ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
INDICES If a is any real number, a ď&#x192;&#x17D; R (a > 0) and n is a positive integer, then đ?&#x2018;&#x17D;đ?&#x2018;&#x203A; = đ?&#x2018;&#x17D; Ă&#x2014; đ?&#x2018;&#x17D; Ă&#x2014; đ?&#x2018;&#x17D; â&#x20AC;Ś Ă&#x2014; đ?&#x2018;&#x17D; đ?&#x2018;&#x203A; đ?&#x2018;Ąđ?&#x2018;&#x2013;đ?&#x2018;&#x161;đ?&#x2018;&#x2019;đ?&#x2018;
The integer n is called the index or exponent and a is the base. ( Read an as â&#x20AC;&#x2DC;a to the nth powerâ&#x20AC;&#x2122;) snashâ&#x20AC;&#x2122;s
n Z ve integer
n0
a
n
n Z (-ve integer)
14 snash’s
For n=0
a 1 , a 0 0
0
0 is not defined. For n positive integer
a n a a a 1st
snash’s
2nd
nth
n factors of a
For n is negative integer ; i.e: n = –m
a
m
a b
1 m a
;
m
m
b a
a0 ; a 0, b 0
x For n is in the form of fraction ;i.e: n y x y
y
1 y
y
a a a a snash’s
x
a y
x
, a 0.
, a0
RULES FOR INDICES 1) 2)
aman amn am
amn
n
a
3)
4)
ab
n
m
a
m
5) snash’s
EXAMPLE 5c)
a
EXAMPLE 5e)
ambm
EXAMPLE 6c)
mn
m
a b
EXAMPLE 5b)
m
a
m
b
, bEXAMPLE 0 6e)
Example 7: Simplify: 1 3
â&#x2C6;&#x2019;
a) 27
1 3
b) 4 2 5
c) đ?&#x2018;&#x17D; â&#x2C6;&#x2122; đ?&#x2018;&#x17D; á đ?&#x2018;&#x17D;
snashâ&#x20AC;&#x2122;s
1 2
d)
3
1 2 5
đ?&#x2018;&#x17D; á đ?&#x2018;&#x17D;đ?&#x2018;&#x203A; â&#x2C6;&#x2122; (đ?&#x2018;&#x17D;â&#x2C6;&#x2019;1 )
1 2
Example 10: đ?&#x2018;Ľ
đ?&#x2018;Ś
đ?&#x2018;§
If 2 = 6 = 12 , prove that đ?&#x2018;§ =
snashâ&#x20AC;&#x2122;s
đ?&#x2018;Ľđ?&#x2018;Ś đ?&#x2018;Ľ+đ?&#x2018;Ś
.
Exercise: Example 8: Simplify: b) 122đ?&#x2018;Ľ+3 â&#x2C6;&#x2122; 6đ?&#x2018;Ľâ&#x2C6;&#x2019;5 â&#x2C6;&#x2122; 82đ?&#x2018;Ľâ&#x2C6;&#x2019;1
c)
â&#x2C6;&#x2019;2 3
3 4
đ?&#x2018;&#x17D; đ?&#x2018;?2 Ă&#x2014; đ?&#x2018;&#x17D; đ?&#x2018;?
2 1 3 2
1 6
á đ?&#x2018;&#x17D; đ?&#x2018;?
10 3
Example 11: Show that 2đ?&#x2018;&#x203A; + 2đ?&#x2018;&#x203A;+1 + 2đ?&#x2018;&#x203A;+2 is divisible by 7 if đ?&#x2018;&#x203A; is a positive integer. snashâ&#x20AC;&#x2122;s
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
SURDS ď&#x201A;§ Surd is a number that contain one or more root sign;
(or radical sign)
ď&#x201A;§ It cannot be simplified into a fraction of two integers,
đ?&#x2018;&#x17D; . đ?&#x2018;?
ď&#x201A;§ Example, 2 is a surd but 4 = 2. ď&#x201A;§ Surd is an irrational number. snashâ&#x20AC;&#x2122;s
4 is not a surd since
SURDS n
n
a
a a
nth root of a
1 n
Surd is expressed in simplest form. For examples: 8 = 4(2) = 2 2
12 25
=
4 3 25
=
2 3 5
Examples of surd: a) 3 b) d) 3+1 d) snash’s
4 5 3+ 5
c) e)
2− 7 3 9
PROPERTIES OF SURD 1)
n
a a m
m
a 3) m b
m
m n
a b
2) m a m b
4)
n m
ab
a mn a
5) a c b c a b snash’s
m
c
Notes: 𝑎 𝑎=𝑎
4 ≠ ±2 but
4 = 2 and − 4 = −2
𝑎±𝑏 ≠ 𝑎± 𝑏 𝑎2 ± 𝑏2 ≠ 𝑎 ± 𝑏 snash’s
Example 12: Identify which of the followings are surd. a) d)
snashâ&#x20AC;&#x2122;s
6 48
b) e)
3
8 3
c) 64
25
Example 13: Simplify: b) 3 10 2 5 d) 3 40 + 20 5
snash’s
18 − 2
Example 14: Simplify:
c)
snashâ&#x20AC;&#x2122;s
3
27đ?&#x2018;Ľ 6 đ?&#x2018;Ś 3 3đ?&#x2018;Ľ 2 đ?&#x2018;Ś 4
Exercise: Example 13: a)
5 3 3
Example 14:
b)
snashâ&#x20AC;&#x2122;s
đ?&#x2018;Ľđ?&#x2018;Ś 3 81đ?&#x2018;Ľ 3 đ?&#x2018;Ś
125
CONJUGATE OF SURD
snash’s
a b
a b
a b
a b
a b
a b
RATIONALISING DENOMINATOR ď&#x192;&#x2DC; process of eliminating surd in denominator so that the denominator is a rational number. ď&#x192;&#x2DC; Simplest form ď&#x192; denominator free from surd
ď&#x192;&#x2DC; Multiplication between conjugates will result in a rational number (no surd expression exists): đ?&#x2018;&#x17D;+ đ?&#x2018;? đ?&#x2018;&#x17D;â&#x2C6;&#x2019; đ?&#x2018;? =đ?&#x2018;&#x17D;â&#x2C6;&#x2019;đ?&#x2018;? đ?&#x2018;&#x17D;+đ?&#x2018;? đ?&#x2018;&#x17D; â&#x2C6;&#x2019; đ?&#x2018;? = đ?&#x2018;&#x17D; â&#x2C6;&#x2019; đ?&#x2018;?2 đ?&#x2018;&#x17D; + đ?&#x2018;? đ?&#x2018;&#x17D; â&#x2C6;&#x2019; đ?&#x2018;? = đ?&#x2018;&#x17D;2 â&#x2C6;&#x2019; đ?&#x2018;? snashâ&#x20AC;&#x2122;s
RATIONALISING DENOMINATOR Problem arise when surd exists in denominator
Solution:
snash’s
Multiply the numerator and denominator by suitable factor
Multiply the numerator and denominator with the conjugate of denominator
Example 15: Simplify the expressions: a)
snashâ&#x20AC;&#x2122;s
5 2đ?&#x2018;&#x17D;
c)
2+ 2 5+ 2
+
2â&#x2C6;&#x2019; 10 3
Example 16: b)
Given
đ?&#x2018;?+ đ?&#x2018;&#x17E; 1â&#x2C6;&#x2019; đ?&#x2018;?
=
4 đ?&#x2018;?+ đ?&#x2018;&#x17E; 1â&#x2C6;&#x2019;đ?&#x2018;?
value of đ?&#x2018;? + đ?&#x2018;&#x17E;.
snashâ&#x20AC;&#x2122;s
and đ?&#x2018;? > 1, find the
Exercise Example 15: Simplify the expression: b)
snash’s
2 2 2−2 3
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
LOGARITHM ď&#x201A;§ A number which is in an index form can be written in a logarithmic form. ď&#x201A;§ x is the logarithm of b to the base a is written as
đ?&#x2018;Ľ = log đ?&#x2018;&#x17D; đ?&#x2018;? and it is equivalent to đ?&#x2018;&#x17D; đ?&#x2018;Ľ = đ?&#x2018;?. đ?&#x2018;&#x17D;đ?&#x2018;Ľ = đ?&#x2018;? â&#x2020;&#x201D;
đ?&#x2018;Ľ = log đ?&#x2018;&#x17D; đ?&#x2018;?
where đ?&#x2018;&#x17D;, đ?&#x2018;? > 0 and đ?&#x2018;&#x17D; â&#x2030; 1. snashâ&#x20AC;&#x2122;s
LOGARITHM 𝑏>0 log 𝑎 𝑏 = 𝑥 𝑎 > 0, 𝑎 ≠ 1
snash’s
LOGARITHM a ď&#x20AC;˝b x
Index Form 32 = 9 91 = 9 5đ?&#x2018;Ľđ?&#x2018;Ś = đ?&#x2018;§ â&#x2C6;&#x2019; 1 đ?&#x2018;Ľ 2 =4
snashâ&#x20AC;&#x2122;s
loga b ď&#x20AC;˝ x Logarithmic Form log 3 9 = 2 log 9 9 = 1 log 5 (đ?&#x2018;§ â&#x2C6;&#x2019; 1) = đ?&#x2018;Ľđ?&#x2018;Ś log 2 4 = đ?&#x2018;Ľ
LOGARITHM ď&#x192;&#x2DC; Logarithmic with base 10 is called common logarithm and it can be written without the base 10:
log10 đ?&#x2018;Ľ = log đ?&#x2018;Ľ ď&#x192;&#x2DC; Logarithmic with base e is called natural logarithm and it can be written as đ?&#x2018;&#x2122;đ?&#x2018;&#x203A;: log đ?&#x2018;&#x2019; đ?&#x2018;Ľ = ln đ?&#x2018;Ľ snashâ&#x20AC;&#x2122;s
LOGARITHMIC RULES Let đ?&#x2018;&#x17D;, đ?&#x2018;Ľ, đ?&#x2018;Ś > 0, đ?&#x2018;&#x17D; â&#x2030; 1 and đ?&#x2018;&#x203A; â&#x2C6;&#x2C6; đ?&#x2018;&#x2026;
1/
loga xy ď&#x20AC;˝ loga x ď&#x20AC;Ť loga y
x 2 / loga ď&#x20AC;˝ loga x ď&#x20AC; loga y y 3 / loga xn ď&#x20AC;˝ nloga x
snashâ&#x20AC;&#x2122;s
4/
loga a ď&#x20AC;˝ 1
5/
loga 1 ď&#x20AC;˝ 0
6/
aloga x ď&#x20AC;˝ x
Example 19: Evaluate without using calculator: b)
snashâ&#x20AC;&#x2122;s
9 log 3 27
d) đ?&#x2018;&#x2019;
ln 4â&#x2C6;&#x2019;ln 24 +2đ?&#x2018;&#x2122;đ?&#x2018;&#x203A;3
Example 20: Expand using the rules of logarithm. a) đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;
snashâ&#x20AC;&#x2122;s
đ?&#x2018;Ľ2đ?&#x2018;Ś 10
c) đ?&#x2018;&#x2122;đ?&#x2018;&#x203A;
đ?&#x2018;Ľ3đ?&#x2018;Ś đ?&#x2018;§
Example 21: Rewrite the following expressions in a single logarithmic expression. b) đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;2 đ?&#x2018;Ľ + đ?&#x2018;Ś + đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;2 đ?&#x2018;Ś â&#x2C6;&#x2019;
snashâ&#x20AC;&#x2122;s
1 đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;2 3
đ?&#x2018;Ľ
CHANGE OF LOG BASE Let 𝑎, 𝑏, 𝑐 > 0, then 𝑙𝑜𝑔𝑐 𝑏 𝑙𝑜𝑔𝑎 𝑏 = 𝑙𝑜𝑔𝑐 𝑎
𝑙𝑜𝑔𝑎 𝑏 = snash’s
1 𝑙𝑜𝑔𝑏 𝑎
Example 22: Evaluate đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;1 70 by converting into ln. Leave the 2
answer in four decimal places. đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;1 70 2
=
đ?&#x2018;&#x2122;đ?&#x2018;&#x203A; 70 1
đ?&#x2018;&#x2122;đ?&#x2018;&#x203A;2
= â&#x2C6;&#x2019;6.1293
snashâ&#x20AC;&#x2122;s
loga x y loga x loga y x loga x loga y loga y n n loga x loga x loga x loga x loga y loga y loga x loga y loga x loga y
loga xy loga x loga y loga 2 x 2loga x
snash’s
Exercise Example 19: Evaluate without using calculator: 1 c) log 5 125 â&#x2C6;&#x2019; log 2 + log 100 16
Example 20: Expand using the rules of logarithm. đ?&#x2018;Śâ&#x2C6;&#x2019;đ?&#x2018;Ľ b) đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;3 đ?&#x2018;Ľđ?&#x2018;Ś
Example 21: Rewrite the following expressions in a single log expression. c) đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;5 2đ?&#x2018;Ľ â&#x2C6;&#x2019; đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;5 3 â&#x2C6;&#x2019; 5đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;5 đ?&#x2018;Ľ snashâ&#x20AC;&#x2122;s
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
INDEX EQUATION COMMON BASE
convert into common base simplify compare index EXAMPLE 9b:
COMMON BASE WITH ± BETWEEN TERMS
convert into common base substitution EXAMPLE 9c:
REMEMBER! an > 0 snash’s
DIFFERENT BASES
cannot be converted into common base take log(or ln) both sides apply log property EXAMPLE 25a:
SURD EQUATION 1 SURD
2 SURDS
3 SURDS
1 surd at one side
1 surd each side
1 surd at one side, 2 surds at the other side
Square both sides and simplify Square both sides again (if there is a remaining surd) Solve the equation EXAMPLE 17b ?
check for validity LHS RHS snash’s
LOG EQUATION 1/COMMON LOG EXPRESSIONS
simplify use antilog or change the base EXAMPLE 23a:
MORE THAN 1 LOG WITH ± BETWEEN TERMS
change the base apply property substitution/ comparison EXAMPLE 23b:
check for validity a, b > 0 for loga b snash’s
Example 26: Solve the simultaneous equations below. b)
snashâ&#x20AC;&#x2122;s
â&#x2C6;&#x2019;2 đ?&#x2018;Ľ â&#x2C6;&#x2019; â&#x2C6;&#x2019;2 đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;đ?&#x2018;Ľ 125 đ?&#x2018;Ľ â&#x2C6;&#x2019;
đ?&#x2018;Ś+2
đ?&#x2018;Ś đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;125 đ?&#x2018;Ľ
=0 =6
Example 18: Find the value(s) of x:
Exercise 3đ?&#x2018;Ľ + 1 â&#x2C6;&#x2019; 2đ?&#x2018;Ľ â&#x2C6;&#x2019; 1 = 1
Example 24: Solve the equation: (3đ?&#x2018;Ľ )2 â&#x2C6;&#x2019;3đ?&#x2018;Ľ+1 + 2 = 0
Example 25: Solve the equation and leave the answer correct to 3 s.f. b) đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;4 3đ?&#x2018;Ľ = 2 + đ?&#x2018;&#x2122;đ?&#x2018;&#x153;đ?&#x2018;&#x201D;4 đ?&#x2018;Ľ + 1 Example 26: Solve the simultaneous equations below. a) 2đ?&#x2018;Ľ + 3đ?&#x2018;Ś = 41 2đ?&#x2018;Ľ+2 + 3đ?&#x2018;Ś+2 = 209 snashâ&#x20AC;&#x2122;s
EXPLORE INDEX You can explore this website for more information: 1. https://revisionmaths.com/gcse-maths-revision/algebra/indices 2. http://mathematics.laerd.com/maths/indices-1.php 3. https://www.youtube.com/watch?v=sbwSKpJkR2s
SURD You can learn more about simplifying surd, the simple fact and history about surd at: http://www.mathslearn.co.uk/core1surds.html LOGARITHM Browse the website to study about the proof of logarithmic rules: https://www.onlinemathlearning.com/logarithms-properties.html SOLVING EQUATIONS You can check your workings and answers for Examples 9, 17, 18, 23, 24 and 25 via the online equation calculator: https://www.symbolab.com/solver/equation-calculator snashâ&#x20AC;&#x2122;s
ℝ
ℚ ℂ ℝℝ ℂ ℝ ℚ′ ℕ ℕ ℤ ℕ ℚ ℤ
ℤ
ℚ
ℕ ℚ′
ℝ
ℚ′
ℂ
ℕ
ℂ
ℚ
ℚ
ℤ
ℚ′
ℚ ℝ
ℕℚ′ℝ ℝℂ ℚ′
ℚ′ ℕ ℂ
ℂ
ℝ
ℕ
ℚ ℤ
ℚ
ℝ
snash’s
IMAGINARY NUMBER i 1
i 1 2
i 3 i 2 i i
i i 4
2
2
1 1
i 5 i 41 i 4 i i
snash’s
2
Example 28: Write the following imaginary numbers in the form of đ?&#x2018;&#x2013;. a) â&#x2C6;&#x2019;6 b) â&#x2C6;&#x2019; â&#x2C6;&#x2019;3 c) â&#x2C6;&#x2019;4.656 d) â&#x2C6;&#x2019;16
snashâ&#x20AC;&#x2122;s
COMPLEX NUMBER complex number = real part + (imaginary part)(imaginary number) z = a + bi a = Re (z) b = Im (z) a + bi
â&#x2C6;&#x2019;đ?&#x;?
real part imaginary part snashâ&#x20AC;&#x2122;s
COMPLEX NUMBER Set of complex number is denoted by C or Complex Real Part Number26
snashâ&#x20AC;&#x2122;s
Imaginary Part
Note
đ?&#x2018;&#x17D; and đ?&#x2018;? are real numbers đ?&#x2018;&#x17D; and đ?&#x2018;? are real numbers đ?&#x2018;&#x17D;=đ?&#x2018;? =0 Purely Real Purely Imaginary
2 â&#x2C6;&#x2019; 4đ?&#x2018;&#x2013;
2
-4
1 1 + đ?&#x2018;&#x2013; 4 3 0 + 0đ?&#x2018;&#x2013; 5 â&#x2C6;&#x2019;6i
1 4 0 5 0
1 3 0 0 â&#x2C6;&#x2019;6
Equality of a Complex Number:
đ?&#x2018;&#x17D; + đ?&#x2018;?đ?&#x2018;&#x2013; = đ?&#x2018;? + đ?&#x2018;&#x2018;đ?&#x2018;&#x2013; if and only if đ?&#x2018;&#x17D; = đ?&#x2018;? and đ?&#x2018;? = đ?&#x2018;&#x2018;.
Zeros of a Complex Number:
đ?&#x2018;§ = đ?&#x2018;&#x17D; + đ?&#x2018;?đ?&#x2018;&#x2013; = 0
snashâ&#x20AC;&#x2122;s
if and only if đ?&#x2018;&#x17D; = 0 and đ?&#x2018;? = 0.
CONJUGATE OF COMPLEX NUMBER Suppose z = a + bi, then the conjugate of z is given by:
z a bi • Conjugate of a complex number is a complex
number where i is being replaced by –i • i,e change the sign of imaginary part
snash’s
snashâ&#x20AC;&#x2122;s
Complex Number 2 + 4đ?&#x2018;&#x2013;
Conjugate 2 â&#x2C6;&#x2019; 4đ?&#x2018;&#x2013;
1 1 â&#x2C6;&#x2019; đ?&#x2018;&#x2013; 4 3
1 1 + đ?&#x2018;&#x2013; 4 3
â&#x2C6;&#x2019;1 + 9đ?&#x2018;&#x2013;
â&#x2C6;&#x2019;1 â&#x2C6;&#x2019; 9đ?&#x2018;&#x2013;
5
5
â&#x2C6;&#x2019;10đ?&#x2018;&#x2013;
10đ?&#x2018;&#x2013;
CONJUGATE OF COMPLEX NUMBER Suppose z = a + bi, then the conjugate of z is given by:
z a bi Properties:
z z 2a z z a b 2
snash’s
2
Example: If ๐ ง = 2 + 3๐ , find:
snashโ s
a)
โ z
b)
๐ งาง
c)
z + ๐ งาง
d)
๐ ง๐ งาง
OPERATIONS OF COMPLEX NUMBERS
snash’s
ADDITION +
SUBTRACTION -
MULTIPLICATION ×
DIVISION ÷
Let z1 a ib
and
z2 c id
z1 z2
a ib c id a c i b d
example 29 : example 30 : 3 2i 1 7i3 5i 4 3i
3 1 i 2 7 3 4 i 5 3 4 9i
1 8i operation
snash’s
z1z2
a ib c id ac i bc ad i2 bd ac bd i bc ad
example 32 :
3 2i1 7i 3 2i 21i 14i2 3 23i 14 1 11 23i snash’s
operation
z1 z2
a ib c id a ib c id c id c id
rationalizing denominator Multiply with conjugate
example 36 : 5 2i 7 4i 35 14i 20i 8i2 = 7 4i 7 4i 72 42
35 8 6i = 49 16 operation
snash’s
Example 31: Find
a)
Exercise
1 + 3đ?&#x2018;&#x2013; + 5 â&#x2C6;&#x2019; 2đ?&#x2018;&#x2013;
b)
2 3
1 2
3+đ?&#x2018;&#x2013; â&#x2C6;&#x2019; â&#x2C6;&#x2019; + đ?&#x2018;&#x2013;
Example 33: Multiply each of the following and write the answers in standard form. b) 3 â&#x2C6;&#x2019; 4đ?&#x2018;&#x2013; â&#x2C6;&#x2019;4 + 3đ?&#x2018;&#x2013; c) 5 â&#x2C6;&#x2019; 2đ?&#x2018;&#x2013; 7đ?&#x2018;&#x2013; Example 35: Find the product of the following complex number and its conjugate. a) 2 â&#x2C6;&#x2019; 3đ?&#x2018;&#x2013; 2 + 3đ?&#x2018;&#x2013; b) â&#x2C6;&#x2019;9 + 2đ?&#x2018;&#x2013; â&#x2C6;&#x2019;9 â&#x2C6;&#x2019; 2đ?&#x2018;&#x2013; Example 37: Express the following in the form of đ?&#x2018;&#x17D; + đ?&#x2018;?đ?&#x2018;&#x2013;: b) snashâ&#x20AC;&#x2122;s
4đ?&#x2018;&#x2013; 1+2đ?&#x2018;&#x2013;
d)
7â&#x2C6;&#x2019;4đ?&#x2018;&#x2013; 2đ?&#x2018;&#x2013;
ARGAND DIAGRAM • Complex numbers can be shown on the complex number plane known as an Argand diagram • Each number is represented by a point.
• The real part is plotted on the horizontal axis and the imaginary part on the vertical axis.
• Sometimes the number itself is represented as a line from the origin to the point. snash’s
𝐼𝑚(𝑧)
𝑏
(𝑎, 𝑏) 𝑧 = 𝑎 + 𝑏𝑖
𝑎
−𝑏
snash’s
(𝑎, −𝑏) 𝑧 = 𝑎 − 𝑏𝑖
𝑅𝑒(𝑧)
Example 38: Plot the following complex numbers on an Argand diagram. a) b) e)
snashâ&#x20AC;&#x2122;s
2 + 3đ?&#x2018;&#x2014; 2 â&#x2C6;&#x2019; 3đ?&#x2018;&#x2014; â&#x2C6;&#x2019;5 + 0đ?&#x2018;&#x2014;
b b2 4ac x 2a
snash’s
EQUATION OF COMPLEX NUMBER
Solving Quadratic equation when discriminant is negative
Equality of Complex numbers Find the value(s) of unknown
z1 z2 a bi c di ac bd
Example 40: Solve the equation đ?&#x2018;Ľ 2 â&#x2C6;&#x2019; 4đ?&#x2018;Ľ + 13 = 0 in the complex
number system.
snashâ&#x20AC;&#x2122;s
Example: Solve for p where 𝑝 ∈ 𝐶 3 − 4𝑖 + 𝑝 2 + 𝑖 = 4 + 3𝑖 let p a 3bi 4i p 2 i 4 3i p 2 i 4 3i 3 4i 2 7i i2 i4 3i 3 4i a bi1 p 2i 2 i 3 4i 2a 2bi ai b 4 3i 2 14i i 7 3 2a bp i 4 2b a 4 3i 4 1 3 2a b 49 13 4 2b a 3 p i 2a b 1 5 51 a 2b 7 snash’s
2
Example 42: Find the square roots of 3 â&#x2C6;&#x2019; 4đ?&#x2018;&#x2013;.
snashâ&#x20AC;&#x2122;s
Exercise Example 38: Plot the following complex numbers on an Argand diagram. c) â&#x2C6;&#x2019;3 + 2đ?&#x2018;&#x2014; d) â&#x2C6;&#x2019;3 â&#x2C6;&#x2019; 2đ?&#x2018;&#x2014; f) 0 + 5đ?&#x2018;&#x2014; Example 41: Solve the equation đ?&#x2018;Ľ 2 â&#x2C6;&#x2019; 3đ?&#x2018;Ľ + 9 = 0 in the complex number system. Example 42: â&#x20AC;Ś .Use the results to solve the quadratic equation (2 â&#x2C6;&#x2019; đ?&#x2018;&#x2013;)đ?&#x2018;Ľ 2 +(4 + 3đ?&#x2018;&#x2013;)đ?&#x2018;Ľ + (â&#x2C6;&#x2019;1 + 3đ?&#x2018;&#x2013;) = 0. snashâ&#x20AC;&#x2122;s