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Form 1 MathematicsChapter 2 and Chapter 4
Correction of Open Book Quiz (Chapter 1)◦ Today!!!
Correction and Parent Signature of Close Book Quiz (Chapter 1)
◦ 24 Oct (Wed) Standard Homework (I) – Orange
◦ 24 Oct (Wed) You must hand in on time!
Result of Close Book Quiz◦ Full mark: 36 (not 40!) and 10 bonus◦ Highest: 44◦ Lowest: 11◦ Average: 24.7◦ Number of students below 20: 11
Major Problems◦ Careless Mistakes!◦ Wrong calculations!◦ No English answers
Result of Close Book Quiz 5th place: LAW Cheuk Hang Ellis
WONG Pui Yin, Paul 4th place: WU SHAN Hao Yi 3rd place: FU Ling Yin 2nd place: LI Ming Chun Edward 1st place: LI Sai Kong
Congratulations!!!!!! Well done!!!!!!
Restaurant problem:◦ 3 students went to a restaurant for a meal of
$250.◦ Everyone firstly paid $100. So, totally $300◦ When the waiter came back with $50, they
decided to get $30 back (everyone gets $10 back) and then left $20 for tips.
◦ So, every student paid $90 only. Now, $90 x 3 + $20 = $290! Where is the last $10?
Money is there! Only the calculation is wrong! The money given by the students (-)
◦ $90 x 3 = $270 The money goes to (+)
◦ $250 (to meal) + $20 (to waiter) = $270! So, the information is correct. The only problem is we have mixed up the
calculation! If we can understand better Directed
Number, we will not have this problem!
Ronald HUI
Arithmetic Operations “+” – Addition
◦ Add… to… Plus Sum “–” – Subtraction
◦ Subtract… from… Minus Difference “x” – Multiplication
◦ Multiply… by… Times Product “” – Division
◦ Divide… by… Over Quotient “=“ – Equals/ is equal to
( + ) ( + ) = ( + ) ( – ) ( – ) = ( + )
( + ) ( – ) = ( – ) ( – ) ( + ) = ( – )
正正得正 負負得正正負得負 負正得負
( + ) ( + ) = ( + )
( – ) ( – ) = ( + )
( + ) ( – ) = ( – )
( – ) ( + ) = ( – )
(+ A) + (+ B) = A + B
(+ A) + (– B) = A – B
(– A) + (+ B) = – A + B
(– A) + (– B) = – A – B
(+ A) – (+ B) = A – B
(+ A) – (– B) = A + B
(– A) – (+ B) = – A – B
(– A) – (– B) = – A + B
( + ) ( + ) = ( + )
( – ) ( – ) = ( + )
( + ) ( – ) = ( – )
( – ) ( + ) = ( – )
(+ A) (+ B) = A B
(+ A) (– B) = – (A B)
(– A) (+ B) = – (A B)
(– A) (– B) = A B(+ A) (+ B) = A B
(+ A) (– B) = – (A B)
(– A) (+ B) = – (A B)
(– A) (– B) = A B
Ronald HUI
Consider A as a variable ( 變數 ) We know 3A = A + A + A or 3A = 3 A So, can we write:
A 7 = A7 or A 7 = 7A ? Which is correct:
B A = BA or B A = AB ? How about:
3A 4B? 3A4B / 12AB / 12BA / AB12 What if -3A -4B?
Ronald HUI
Pay attention to the followings: Consider A as a variable ( 變數 ) 1 A = A A + A + A = 3A A A A = A3
3A 4A = 12A2
Ronald HUI
When we work on the followings, we should put together the like terms and then simplify!
For examples:1. A +2B +3A +4B = A +3A +2B +4B
= 4A + 6B2. A -2B –3A +4B = A -3A -2B +4B
= (A-3A) + (-2B+4B)= (-2A) + (2B)= -2A +2B
Page 77 of Textbook 1A◦ Class Practice
Ronald HUI
Addition of equality ( 等量相加 )X – 7 = 2
X -7 +7 = 2 +7 X = 9
X – 7 = 2 X = 2 +7 X = 9
Ronald HUI
Subtraction of equality ( 等量相減 )X + 7 = 12
X +7 - 7 = 12 -7 X = 5
X + 7 = 12 X = 12 -7 X = 5
Ronald HUI
Multiplication of equality ( 等量相乘 )X 5 = 4
X 5 5 = 4 5 X = 20
X 5 = 4 X = 4 5 X = 20
Ronald HUI
Division of equality ( 等量相除 ) 5X = 20
5X 5 = 20 5 X = 4
5X = 20 X = 20 5 X = 4
Page 91 of Textbook 1A◦ Class Practice
Ronald HUI
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
If the sum of 3 consecutive ( 連續 ) numbers are 69, find these numbers.
Let x be the smallest number.Then, x+1 and x+2 are the next 2 numbers
Then, x + (x+1) + (x+2) = 69x + x +1 + x + 2 = 69x + x + x + 1 + 2 = 69
3x = 66 => x = 22.
So, the numbers are 22, 23 and 24.
Page 99 of Textbook 1A◦ Questions 3 – 9
Correction of Open Book Quiz (Chapter 1)◦ Today!!!
Correction and Parent Signature of Close Book Quiz (Chapter 1)
◦ 24 Oct (Wed) Standard Homework (I) – Orange
◦ 24 Oct (Wed) You must hand in on time!
Good Luck!
Enjoy the world of Mathematics!
Ronald HUI
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