Form 1 Mathematics Chapter 2 and Chapter 4. Ronald HUI When we work on the followings, we should put together the like terms and then simplify! For.

Form 1 MathematicsChapter 2 and Chapter 4

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

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

If a = bThen a + c = b + c

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

If a = bThen a - c = b - c

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

If a = bThen ac = bc

Ronald HUI

Division of equality ( 等量相除 ) 5X = 20

5X 5 = 20 5 X = 4

5X = 20 X = 20 5 X = 4

If a = bThen a c = b c(but c 0)

Ronald HUI

Distributive Law ( 分配律 ) 5 (X+2) = 205 (X) + 5 (2) = 20

5X+10 = 20 5X = 10

X = 2

a(b + c) = ab + ac(a + b)c = ac + bc

Ronald HUI

Distributive Law ( 分配律 ) -5 (X-2) = 20(-5) (X) – (-5) (2) = 20

-5X+10 = 20 -5X = 10

X = -2

-a(b + c) = -ab - ac-a(b - c) = -ab + ac

Ronald HUI

Cross Method ( 交义相乘 )

If a c = b dThen ad = bc(but c0 and d0)

15

28

2815

47355

7

4

3

x

x

x

x

Page 94 of Textbook 1A◦ Class Practice

Page 94 of Textbook 1A◦ Questions 16, 19, 22

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 SHW (I) – Orange◦ 29 Oct (Monday)

WB P.39-40, 42-43◦ 29 Oct (Monday)

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