E

1 aren't going to play

2 isn't going to walk

3 am not going to have

4 is going 

5 am going to watch

6 aren't going

7 am not going to finish

8 are not going to buy

Bài 3 : 

(A) : Fe3O4

(B) : FeO

(D)  : Fe

(E) : FeS

(F)  : SO2

(G) : SO3

(H) : H2SO4

\(3Fe_2O_3 + CO \xrightarrow{t^o} 2Fe_3O_4 + CO_2\\ Fe_3O_4 + CO \xrightarrow{t^o} 3FeO + CO_2\\ FeO + CO \xrightarrow{t^o} Fe +C O_2\\ Fe + S \xrightarrow{t^o} FeS\\ 4FeS +75O_2 \xrightarrow{t^o} 2Fe_2O_3 +4SO_2\\ 2SO_2 + O_2 \xrightarrow{t^o} 2SO_3\\ SO_3 + H_2O \to H_2SO_4\\ 2FeS + 10H_2SO_4 \to Fe_2(SO_4)_3 + 9SO_2 + 10H_2O\)

Bài 4 : 

(A) : S

(B) : H2

(C) : O2

(D) : SO2

(E) : H2S

(F) : H2SO4

(G) : K2SO4

(H) : MnSO4

\(S + O_2 \xrightarrow{t^o} SO_2\\ S + H_2 \xrightarrow{t^o} H_2S\\ S + 2H_2SO_4 \to 3SO_2 + 2H_2O\\ SO_2 + 2H_2S \to3 S +2 H_2O\\ 5SO_2 +2 KMnO_4 + 2H_2O \to K_2SO_4 + 2MnSO_4 + 2H_2SO_4\)

\(\left\{{}\begin{matrix}2x+y=1\\x+y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\x+y=-1\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=2\\y=-3\end{matrix}\right.\)

\(\left\{{}\begin{matrix}2x+2y=18\\x-y=-6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x+y=9\\x-y=-6\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}2x=3\\x-y=-6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{2}\\y=\dfrac{15}{2}\end{matrix}\right.\)\(\left\{{}\begin{matrix}2x+3y=6\\x-2y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}4x+6y=12\\3x-6y=9\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}7x=21\\3x-6y=9\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=3\\y=0\end{matrix}\right.\)

1 makes

2 doesn't eat

3 goes

4 Do-go

5 Do-agree

6 does-come

7 does-work

8 doesn't -water

9 do-do

10 Do they eat

11 am 

12 rises

13 is

14 doesn't read

15 watches

Ex2

1. you don't go to school everyweekday

Do you go to school every weekday?

2. Lan doesn't play badminton with her friends today

Does Lan  play badminton with her friends today?

3. Hoa doesn't like reading story books

Does Hoa like reading story books

4. Lien and Lan don't in the same class

Do Lien and Lan in the same class

5.  Ba's father doesn't work in a big factory with my father

Does  Ba's father work in a big factory with my father

6 She doesn't study English very well

Does she study English very well

7 They don't tall and thin

Do they tall and thin

8 His mother doesn't cook dinner for the family everyday

Does his mother cook dinner for the family everyday

9 Hoa's mother doesn't go shopping this morning

Ex3

1. Lan usually reads book recess

2 Does Ba go to the market every Sunday

3 Her father often rides his motorbike

4 Nam doesn't have short black hair

5 She usually gets up early

a A>B

b C>D 

c D<E

4:

a: A=1/3(1+1/2+...+1/64)

Đặt B=1+1/2+...+1/64

=>2B=2+1+...+1/32

=>B=2-1/64=127/64

=>A=1/3*127/64=127/192

b: =5/2(1-1/3+1/3-1/5+...+1/11-1/13)

=5/2*12/13

=60/26=30/13

chữ xấu dữ vậy

Bài 3: 

a: Ta có: \(x^2+5x+5xy+25y\)

\(=x\left(x+5\right)+5y\left(x+5\right)\)

\(=\left(x+5\right)\left(x+5y\right)\)

b: Ta có: \(x^2-y^2+14x+49\)

\(=\left(x+7\right)^2-y^2\)

\(=\left(x+7-y\right)\left(x+7+y\right)\)