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Form 1 Mathematics
Chapter 2 and Chapter 4
Correction of SHW (I) – Orange
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Today!
WB P.39-40, 42-43
Today!
SHW (II) – Yellow
30 Oct (Tuesday)
WB P.46-47
31 Oct (Wednesday)
Open Book Quiz
31 Oct (Wednesday)
You must hand in on time!
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Distributive Law (分配律)
5 (X+2) = 20
5 (X) + 5 (2) = 20
a(b + c) = ab + ac
5X+10 = 20
(a + b)c = ac + bc
5X = 10
X=2
Ronald HUI
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Distributive Law (分配律)
-5 (X-2) = 20
(-5) (X) – (-5) (2) = 20
-a(b + c) = -ab - ac
-5X+10 = 20 -a(b - c) = -ab + ac
-5X = 10
X = -2
Ronald HUI
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Cross Method (交义相乘)
3x 7
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4 5
5 3 x   7  4
15 x  28
28
x
15
If
a  c = b  d
Then
ad = bc
(but c0 and d0)
Ronald HUI
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Page 94 of Textbook 1A
◦ Class Practice
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Page 94 of Textbook 1A
◦ Questions 16, 19, 22
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Use a letter x to represent unknown number
設 x 為變數 (即想求的答案)
Follow the question and form an equation
根據問題，製造算式
Solve for x
算出 x 的值
Write answer in words (with units!)
寫出答案 (包括單位)
Ronald HUI
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Page 99 Question 3:
◦ If the sum of two consecutive natural numbers is 37,
find the smaller number
◦ Step 1: Let x be the smaller number.
◦ Step 2: Then, the larger number will be x + 1
So, x + (x + 1) = 37
◦ Step 3:
x + x + 1 = 37
2x = 36
x = 18
◦ Step 4: Therefore, the smaller number is 18.
◦ Checking:
18 + 19 = 37!
Ronald HUI
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Page 99 of Textbook 1A
◦ Questions 4 – 9
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Page 99 Question 4:
◦ Add 3 to one half of a number and the sum is 9.
Find that number
◦ Step 1: Let x be the that number.
◦ Step 2: Then, one half of a number will be x/2
So, x/2 + 3 = 9
◦ Step 3:
x/2 = 6
x = 12
◦ Step 4: Therefore, the number is 12.
◦ Checking: 12/2 + 3 = 6 + 3 = 9!
Ronald HUI
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Page 99 Question 5:
◦ The number of candies Susan has is represented by
the algebraic expression 6 + 10x, where x stands
for the number of boxes of candies she buys, If
Susan has 36 candies after the purchases, find the
number of boxes of candies she buys.
◦ Step 1: Given x is the number of boxes.
◦ Step 2: Then, 6 + 10x = 36
◦ Step 3:
10x = 30
x=3
◦ Step 4: Therefore, the number of boxes is 3.
or Susan buys 3 boxes of candies.
Ronald HUI
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Page 99 of Textbook 1A
◦ Questions 6 – 9
WB P.39-40, 42-43
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30 Oct (again!)
SHW (II) – Yellow
30 Oct (Tuesday)
Open Book Quiz
31 Oct (Wednesday)
Close Book Quiz
7 Nov (Wednesday)
You must hand in on time!
Good Luck!
Enjoy the world of Mathematics!
Ronald HUI