A=5x415x99-4x320x89
B=5x29x619-7x229x276
tính a:b
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1 What is your hobby?
2 When did you start your hobby
3 Why do you enjoy your hobby
4 How many hours a day do you spend on your hobby
5 What does Jim usually do in his free time
6 How often does he play volleyball
7 Where does he often play volleyball
8 Who does he like to play volleyball with
I. Write questions for the underlined parts.
1. A: What is your hobby
B: My hobby is photography.
2. A:When did you started yor hobby
B: I started my hobby five years ago.
3. A:why do you enjoy your hobby
B: I enjoy my hobby because I think it’s creative.
4. A:How many hours a day fo you spend on your hobby
B: I spend two hours a day on my hobby.
5. A:What does Jim ussually do in his free time
B: Jim usually plays volleyball in his free time.
6. A:How often does he play volleyball
B: He plays volleyball three times a week.
7. A:Where does he often play volleyball
B: He often plays volleyball at the court near his school.
8. A:Who does he like to play with
B: He likes to play volleyball with his friends.
Chán mớ!
a-b=2a+2b=a:b
a-b=2a+2b
3a=b.
a:b=-3
2.(a+b)=3
a+b=1,5
Có tổng và hiệu của a với b rồi,tự làm nhé!
b tương tự,biến đổi khó hơn,chịu khs=ó nghĩ như câu a nhé!
Chán mớ!
Chúc em học tốt^^
a)a-b=2(a+b)
a-b=2a+2b
=>-b-2b=2a-a
-3b=a
=>a:b=-3
Như vậy a-b=-3
Thay a=-3b vào đẳng thức trên, ta có
-3b-b=-3
-4b=-3
=>b=3/4
a=3/4.(-3)=-9/4
b) ab=a:b =>b=1 hoặc b=-1
Với b=1 thì a+1=a ( loại)
Với b=-1 thì a-1=-a
=>a+a=1
2a=1
a=1/2
Vaayja=1/2 , b=-1
a)a-b=2(a+b)=2a+2b => a=2a+3b => -a=3b => b=-a/3
mà a-b=a:b => a-(-a/3)=a:(-a/3) => 4a/3=-3 => a=-9/4 => b=3/4
b)a+b=ab => a=ab-b=a(b-1) thay vào a:b=a:a(b-1)=b-1
mà a+b=b-1 => a+b=b+(-1) => a=-1 thay vào a+b=ab ta được: (-1)+b=(-1).b
=>b-1=-b=>2b=1=>b=1/2