18. does

19.does

20.do/wath

Có mấy câu trong bài làm của bạn bị sai á, nên là mình làm lại từ câu 1 - 20 luôn =))

1 goes

2 will come

3 studies - isn't studying

4 eats

5 is raining

6 won't rain

7 will help

8 am doing

9 doesn't go

10 doesn't rise

11 won't travel

12 am not playing

13 reads

14 are going to travel

15 am studying

16 works

17 doesn't play

18 Does - rise

19 does - go

20 are - watching

61 to stop talking

62 to be patient

63 to go to her room

64 to hurry up

65 to give him the key

121 if John would get there on time

122 if I didn't know the traffic regulations

123 if their soldiers had enough weapons

124 if I could do my best boys

125 if they were going to start work the next day/ the following day

61 The teacher told Joe to stop talking

62 She told him to be patient

63 Her father told her to go to her room

64 She told us to hurry up

65 He asked her to give him the key

121 She wanted to know if they would get there on time

122 The policeman wondered if I didn't know the traffic regulations

123 The commander wanted to know if their soliders had enough weapons

124 The coach wanted to know if I could do my best?

125 He asked if they were going to start work the day after

1.Mary played the piano while her parents watched Tv

2.She painted a picture while her brother did his homework

3.Jane baked a cake while her has decorated the house

4.They explored the city streets and took photographs all day

5.My sister was playing badminton while my brother is flying his kite

6.Ngoe had an meeting on Wednesday at 9.am

7.Quang read the science book all morning .

Chúc bạn học tốt nhé!

1 Mary was playing piano while her parents were watching TV 

2 She was painting a picture while her brother was doing his homework

3 Jame was baking a cake while her father was decorating the house

4 They were exploring the city streets and taking photographs all day

5 My sister was playing badminton while my brother was flying kite

6 Ngoe was having a meeting at 9 a.m last Wednesday

7 Quang was reading science book all morning

\(2x^2-xy+4x-2y\)

=x(2x-y)+2(2x-y)

=(2x-y)(x+2)

`x^3 + 2x^2 + x + 2 = 0`

`=> (x^3 + 2x^2) + (x + 2) = 0`

`=> x^2 (x+2) + (x+2) = 0`

`=> (x^2 + 1)(x+2) = 0`

Mà `x^2 + 1 > 0`

`=> x+ 2 = 0`

`=> x = -2`

Vậy `x = - 2`

`A = 3 (x + 1)^2 - (x + 3)^2`

`= 3 (x^2+  2x + 1) - (x^2 + 6x + 9)`

`= 3x^2 + 6x + 3 - x^2 - 6x - 9`

`= (3x^2 - x^2) + (6x - 6x) + (3 - 9)`

`= 2x^2 - 6`

Như vậy `A ` vẫn phải phụ thuộc vào `x`

---------------------------

Bạn xem lại đề bài nhé

`(2x - 5y)(2x + 5y)`

`= (2x)^2 - (5y)^2`

`= 4x^2 - 15y^2`

--------------------

`a^2 - b^2 = (a-b)(a+b)`

Với

`a = 2x`

`b = 5y`