Cần bổ sung điều kiện \(x;y\inℤ\)

a) \(\left(x-7\right)\left(xy+1\right)=9=1\cdot9=3\cdot3=\left(-1\right)\cdot\left(-9\right)=\left(-3\right)\cdot\left(-3\right)\)

Xét bảng :

Vì x,y thuộc Z nên ta có (x;y)={(8;1),(16;0),(-2;1),(4;-1)

b) \(\left(x+5\right)\left(3x-12\right)>0\)

TH1 : \(\hept{\begin{cases}x+5>0\\3x-12>0\end{cases}\Leftrightarrow\hept{\begin{cases}x>-5\\x>4\end{cases}\Leftrightarrow x>4}}\)

TH2 : \(\hept{\begin{cases}x+5< 0\\3x-12< 0\end{cases}\Leftrightarrow\hept{\begin{cases}x< -5\\x< 4\end{cases}\Leftrightarrow x< -5}}\)

Vậy....

ko có trắc nghiệm

https://timgiasuhanoi.com/de-thi-hsg-toan-6-huyen-quan-son-thanh-hoa-2018-2019/

dap an co

1 lan was sick so she did not go to school

...Lan did not go to school........because.she was sick........

2 Nobody in my family is older than my grandmother

My grandmother ..is the oldest person in my family......

3 We started learning english when we were in grade 3 

We.started to learn English..........since we were in grade 3

4 There is noise pollution.People and animals have hearing problems

If there is noise pollution, people and animals will have hearing problems

-2.

-1.

0.

1.

2.

3.

4.

5.

6

=0

a, Trên nửa mặt phẳng bờ chứa tia Om có : \(\widehat{mOn}=50^o< \widehat{mOt}=100^o\) nên tia On nằm giữa hai tia Om và Ot 

b, Vì tia On nằm giữa hai tia Om và Ot nên ta có : \(\widehat{mOn}+\widehat{nOt}=\widehat{mOt}\)

Thay số :  \(50^o+\widehat{nOt}=100^o\Leftrightarrow\widehat{nOt}=50^o\)

Vậy : ....

c, Có gì đó sai sai . Đề phải là tia On có phải là tia phân giác của góc \(\widehat{mOt}\). Vì sao ? mới đúng

 + Vì tia On nằm giữa hai tia Ot và Om

 + \(\widehat{mOn}=\widehat{nOt}=50^o\)

Vậy : ....

d, Vì tia Oy là tia phân giác của góc mOn nên ta có :

\(\widehat{mOy}=\widehat{yOn}=\frac{\widehat{mOn}}{2}=\frac{50^o}{2}=25^o\)

Th1 : Tia On nằm giữa hai tia Ot và Oy nên ta có :

     \(\widehat{tOn}+\widehat{nOy}=\widehat{tOy}\)

Thay số : \(50^o+25^o=75^o=\widehat{tOy}\)

Th2 : Tia Oy nằm giữa hai tia Ot và Om nên ta có :

  \(\widehat{tOy}+\widehat{yOm}=\widehat{tOm}\)

Thay số : \(\widehat{tOy}+25^o=100^o\)

\(\Rightarrow\widehat{tOy}=100^o-25^o=75^o\)

Vậy góc tOy = 75^o

1. 

a)

3/4- 3/2+1/2 . 12/5

=-3/4+6/5

=9/20

b)

8 . x-7,8 . x=25

0,2 x= 25

x=25 : 0,2

x=125

c)1/4 . 4/3 . 30. 1/2. 8/45

=8/9

đ)  9/2+ 3/4 x =27/8

              3/4x= -9/8

       x=-9/8 : 3/4

  x=-3/2

 b2:

a) 13/15 . 3/4-(8/15+1/4)

    =39/60  - 47/60

 = -8/60 = -2/15

My house is located in a small quiet alley. That’s a pretty pink house which consists of 6 rooms in totally: a living room, a kitchen, a toilet, a bathroom and two bedrooms. There are a white leather sofa, a television and a sideboard in the living room. After dinner, my father will turn on the television, choose a great movie and we watch it happily. Next to the living room is the kitchen where is used for cooking and enjoying the meals. In the middle of the room is a dinner table which is made from wood. Three cookers, a refrigerator and all the necessary stuff for cooking is arranged carefully in the right corner of the room. In the left of the kitchen is a clean toilet. Beside the toilet is the bathroom which is equipped a shower and a bathtub. There are only two rooms upstairs that is my parents’ room and my private room. I’ve decorated my bedroom with adorable wallpaper and many lovely stuffed animals. A single bed is placed next to the window so that I can stargaze before falling asleep. In the opposite of the bed are my desk and my bookshelf that contains many kinds of book. There are also an old television and a piano in my bedroom. I especially love the piano because that was the gift from dad in my birthday. In every Christmas or Tet holiday, all member of my family ornament the house together and then gather in the kitchen to cooking. Although my house is not too big but to me that is the most beautiful house in the world.

có cần bản dịch ko bn??

kb với mk nha

I love a quite strange sport for everyone, and it is ping pong. Not many people in Vietnam who are interested in ping pong, and it is also hard to find a place to actually have enough equipment to play it. Ping pong, or it also known as table tennis, consists of two or four players hitting a lightweight ball back and forth on a table. The table is divided in two halves by a net, and it marks the playing zone of each team. The basic rule for amateurs is pretty simple as players need to let the ball touch their side of the table one time before bouncing back. They then hit the ball back to their opponent’s side with a small paddle, and this time the ball also need to touch the other side of the table as well. A point is counted when a player fail to return back the ball, let it touch the net, or make it land outside of the table. Since it is played on a table, so the area is not big enough for us to wait and think about the next move. Therefore, we need to play it with fast reactions and nonstop motions. We only have one second to act the next step right after hitting the ball, and it does not take much time to complete a set. In a competition, and match usually consists of five or seven sets, and the first one to score 11 points wins a set. Many people do not take this sport serious, but I think it is a very good sport to train both of our physical and mental health as we need to be tough and have quick reactions at the same time.