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a. Vì bóng đèn mắc nối tiếp nên cđdđ I1, I2:
I = I1 = I2 = 0,2A
b. HĐT U2 giữa hai đầu bóng đèn Đ2:
U2 = U - U1 = 6 - 2,5 = 3,5V
1, chỉ cách làm mẫu nek:
NO+O2=>NO2
NO+O2 là vế 1, NO2 là vế 2
vế 1 : N=1, O=3
vế 2 : N=1, O=2
cân bằng:
vế 2: 2O2( O vế 2 ít ng tử hơn )
lúc này vế 2 có O=4 vàN=2
vế 1: 2NO
lúc này vế 1 N=2, O=4
kl : 2NO+O2=>2NO2
2 , làm y như nãy:
4P+5O2=>2P2O5
3, Fe2O3+3H2SO4=>Fe(SO4)3+3H2O
1 If you are Vietnamese, you should know the story of Chung cakes and Day cakes
2 What leisure activity o you think is the best for teenagers?
3 People in rural areas often talk more optimistically about the future than city people
4 Do we have to follow the tradition of cleaning the house before Tet
5 Unlike many other jobs, farmers depend heavily on the weather
6 Medical help can be obtained more easily in a city than in the countryside
7 In our country, it is against the law to discriminate against any ethnic or religious group
8 What are the benefits of using computers or mobile phones for leisure activities?
9 In Viet Nam, you should wait for the eldest person before you sit down
10 Many ethnic groups have their own languages, and some even have written languages
1.If you are Vietnamese,you should know the story of chung cakes and day cakes.
2.what leisure activity do you think is the best for teenagers?
3.People in the rural areas of Britain talk about the future more optimistically than city people.
4.Do we have to follow the tradition of cleaning the house before Tet.
5.Unlike many jobs,farmers depend heavily on the weather.
Bài 3:
a: \(M=5+5^2+5^3+...+5^{99}+5^{100}\)
\(=5\left(1+5\right)+...+5^{99}\left(1+5\right)\)
\(=6\cdot\left(5+...+5^{99}\right)⋮6\)
b: \(N=1+4+4^2+...+4^{62}\)
\(=\left(1+4+4^2\right)+...+4^{60}\left(1+4+4^2\right)\)
\(=21\cdot\left(1+...+4^{60}\right)⋮21\)