form 1 mathematics chapter 2 and chapter 4. ronald hui when we work on the followings, we should...
TRANSCRIPT
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
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.
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!