3. WARM UP
An adult panda eats 15kg bamboo each day. There are 5 adult
pandas and 2 little pandas in Beijing Zoo. The poor breeder
there must prepare 89kg bamboo for all the pandas every day.
How much bamboo should a little panda eat per day?
Define Let x= the bamboo a
little panda eats per day
15×5 + 2 x = 89
(1) How many variables are
there?
One, x
(2) What is the degree of this
variable x?
1
4. I. 一元一次方程
LINEAR EQUATION IN ONE VARIABLE
一元一次方程:只含有一个未知数,且含有未知数的
项的次数是一次的方程.
如15 × 5 + 2 𝑥 = 89, 5𝑥 = 0,3 + 𝑥 = 0等,都是一
元一次方程.
2𝑦 − 3 = 5𝑦 + 6 ??? √ One variable Linear Equation:
One variable
The highest degree is 1
10. P6. In the equation 𝑎2𝑥2
− 𝑥2
+ 𝑥 − 𝑎𝑥 − 3 = 0, a is
a number. Find the value of a to make the equation
a linear equation. Find x.
Challenge for S+
Solution : 𝑎2 − 1 𝑥2 + 1 − a 𝑥 − 3 = 0
𝑎2 − 1 = 0; 1 − 𝑎 ≠ 0
𝑎 = −1
The highest degree of
x is 1
11. P7. Solve the equation : 4𝑥 = 18 − 2𝑥
解: 根据等式性质,在等式两边同时加上𝟐𝒙
得 4𝑥 + 𝟐𝒙 = 18 − 2𝑥 + 𝟐𝒙
𝟒𝒙 + 𝟐𝒙 = 𝟏𝟖
6𝑥 = 18
𝑥 = 3
移项
检验:将x=3分别带入原方程的两边
𝐿𝑒𝑓𝑡: 4 × 3 = 12 𝑅𝑖𝑔ℎ𝑡: 18 − 2 × 3 = 12
Left = right = 12
So x=3 is the solution.
Original
equation
Combine like
terms
4𝑥 = 18−2𝑥
化简:合并一次/
同类项
II. SOLVE EQUATIONS
22. III.关于AX=B的讨论
The equation has infinitely many solutions.
The equation is an identity.
P𝟏𝟕. 3 4x − 2 = −2 −6x + 3
12x − 6 = 12x − 6
0 ∙ x = 0 left always = 𝒓𝒊𝒈𝒉𝒕
Solution: All Real Numbers (A.R.N.)
对于方程ax=b,当a=0且b=0时,
则方程的解为A.R.N. (所有实数解)
23. It has no solution
P1𝟖. 2𝑛 + 4 𝑛 − 2 = 8 + 6𝑛
6𝑛 − 8 = 8 + 6𝑛
0 ∙ 𝑛 ≠ 16
left ≠ 𝒓𝒊𝒈𝒉𝒕
对于方程ax=b,当a=0且b≠ 0时,
则方程的解为No Solution(无解)
24. P𝟏𝟗. Solve each equation. If the equation is an identity,
write “A.R.N”; if it has no solution, write “no solution”.
1) 3 m + 1.5 = 1.5(2m + 3)
2)
1
2
h +
1
3
h − 6 =
5
6
h + 2
3)
x+1
2
+
x−1
3
− 2 =
2x+1
6
A.R.N.
No solution
𝑥 = 4
25. Conclusion
Given that 𝒂𝒙 = 𝒃
One solution
X=
𝑏
𝑎
All Real Number No Solution
𝒂 ≠ 𝟎 𝒂 = 𝟎 & 𝒃 = 𝟎 𝒂 = 𝟎 & 𝒃 ≠ 𝟎
27. P𝟐𝟏. Solve the equation for 𝑥 and discuss solutions in
different cases.
𝑎 𝑥 − 𝑏 = 𝑏(𝑥 + 𝑎)
𝑎 − 𝑏 𝑥 = 2𝑎𝑏
Solution:
If 𝑎 ≠ 𝑏, then 𝑥 =
2𝑎𝑏
𝑎−𝑏
(𝑜𝑛𝑙𝑦 𝑜𝑛𝑒 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛)
If 𝑎 = 𝑏 ≠ 0, then NS (No solution)
If 𝑎 = 𝑏 = 0, then ARN (Infinitely many solutions)
Challenge for S+
28. 1. 一元一次方程 Linear Equation
1. 解一元一次方程
2. 关于ax=b的讨论,Given that 𝒂𝒙=𝒃
One variable; the highest degree is 1
SUMMARY