Download Directed Numbers

Form 1 Mathematics
Chapter 2 and Chapter 4

“>”: Greater than

“<”: Less than

“”: Greater than or equal to (or Not less than)
◦ A combination of “>” and “=”

“”: Less than or equal to (or Not greater than)
◦ A combination of “<“ and “=”
Ronald HUI





P.166 Question 9: Add 5 to 4 times of a
number p and the sum is greater than 33.
Add 5
4 times of a number p
The sum
Then, the inequality is




“+5”
“4p”
“4p+5”
“4p+5 > 33”
Ronald HUI

P.166 Question 11: When the sum of a
number s and 3 is multiplied by 2, the
product is smaller than -10.

The sum of s and 3  “s+3”
Multiplied by 2
 “2”
The product
 “(s+3) 2” or 2(s+3)
The inequality is
 “2(s+3) < -10”

Write 3 numbers



 by guessing!
Ronald HUI






P.166 Question 13a: Mike has 2 packs of $1.9
stamps, 1 pack of $2.4 stamps and y packs of
$1.4 stamps. Each pack contains 10 pieces of
stamps. Write an inequality…
2 packs of $1.9
1 pack of $2.4
y packs of $1.4
Total value
The inequality is





2  $1.9  10 = $38
1  $2.4  10 = $24
y  $1.4  10 = $14y
$38+$24+$14y
$38+$24+$14y <$100
or
14y+62 < 100
Ronald HUI





P.166 Question 13b: Find the value of y if the
total value of the stamps that Mike has is $76.
Total value
The equation is
 $38+$24+$14y
 $38+$24+$14y = $76
or
14y+62 = 76
14y = 14
y=1
Therefore, y = 1.
or “Mike has one pack of $1.4 stamps.”
Ronald HUI






Some special terms:
One half = 二分之一
One third = 三分之一
One quarter / One fourth = 四分之一
One fifth = 五分之一
First, Second, Third, Fourth, Fifth,
Sixth, Seventh, Eighth, Ninth, Tenth,
Eleventh, Twelfth, Thirteenth, Fourteenth, …
Ronald HUI

Page 165 of Textbook 1A
◦ Questions 1 - 8

Page 77 of WB 1A  Homework
◦ Questions 1 - 4

A formula is an equation with
◦ At least 1 variables on the right of equal sign.
◦ Only 1 variable (Subject) on the left of equal sign.

e.g. A = (U + L)  H  2
◦ A is the subject of the formula
◦ U, L and H are the variables of the formula

Do you know what this formula means?
Ronald HUI





P.169 Question 18: v = u + gt
(u = -8, g = 10, t = 3, v = ?)
v = u + gt
= (-8) + (10) (3)  Method of substitution
= -8 + 30
= 22
Ronald HUI

P.169 Question 20: In the formula
S=88+0.5t , if S=120, find the value of t.
S = 88 + 0.5t
(120) = 88 + 0.5t
120 - 88 = 0.5t
32 = 0.5t
32  2 = t
64 = t
t = 64
Ronald HUI

P.169 Question 22a: It is given that V=Ah3.
If V = 40 and h = 6, find the value of A.
V = Ah  3
(40) = A (6)  3
40  3 = 6A
120 = 6A
120  6 = A
20 = A
A = 20
Ronald HUI


P.169 Question 22b: It is given that V=Ah3.
Find the value of h such that A = 5 and the
value of V is half of that given in (a)
In (a), V = 40. So, in (b), V = 20.
V = Ah  3
(20) = (5) h  3
20  3 = 5h
60 = 5h
60  5 = h
h = 12
Ronald HUI

Page 169 of Textbook 1A
◦ Questions 5 - 14

Pages 80-81 of WB 1A  Homework
◦ Questions 1 - 5







Consider a sequence: 2, 4, 6, 8, 10, …
Can you guess what are the next numbers?
What is the 10th term?
What is the 100th term?
What is the nth term?
1, 2, 3, 4, 5, …, 10, …, 100, …, n (第幾個)
2, 4, 6, 8, 10, …, 20, …, 200, …, 2n (答案)
Ronald HUI






A Sequence is a group of numbers with
number pattern.
Each number in the sequence is called a Term.
The first one in the sequence is called the
First Term.
In the sequence, 2, 4, 6, 8, 10, …
2 is the first term, 4 is the 2nd term, 6 is …
The general term (通項) is 2n or an=2n
Ronald HUI







What is the NEXT TWO terms of the following
sequences?
4, 8, 12, 16, 20, …
12, 24, 36, 48, 60, …
-1, -2, -3, -4, -5, …
5, 6, 7, 8, 9, …
6, 8, 10, 12, 14, …
-20, -10, 0, 10, 20, …
Ronald HUI







What is the GENERAL terms of the following
sequences?
4, 8, 12, 16, 20, …
12, 24, 36, 48, 60, …
-1, -2, -3, -4, -5, …
5, 6, 7, 8, 9, …
6, 8, 10, 12, 14, …
-20, -10, 0, 10, 20, …
Ronald HUI



Given a general term: an=2n-1
What is the first 5 terms?
The first 5 terms are:
◦
◦
◦
◦
◦


a1
a2
a3
a4
a5
=
=
=
=
=
2(1)-1
2(2)-1
2(3)-1
2(4)-1
2(5)-1
=
=
=
=
=
1
3
5
7
9
What is the 17th term?
The 17th term is a17 = 2(17)-1 = 33
Ronald HUI

Pages 83 - 84 of WB 1A
◦ Questions 1 - 4

Page 175 of Textbook 1A
◦ Questions 1 - 12
Folder

◦

◦

◦

◦

◦

13 Nov (Tuesday)
WB (P.77, 80, 81)
13 Nov (Tuesday)
SHW (III) (Chapter 4)
14 Nov (Wednesday)
Open Book Quiz (Chapter 4)
14 Nov (Wednesday)
Close Book Quiz (Chapter 4)
21 Nov (Wednesday)
You must hand in on time!
Good Luck!
Enjoy the world of Mathematics!
Ronald HUI