`-2^(n+2)-2^n

=-(2^(n+2)+2^n)`

=-(2^n .2^2 +2^n)`

`=-2^n .(2^2+1)`

1. is calling

2. are you doing

3. Do you want

4. need 

5. don't know

6. is singing 

1. I am saving money to buy his pictures because I like them.

2. Many students study this language since they need it.

3. I spend most of my time studying English as my work requires a fluent English.

4. He wants to take me home now that it is going to rain.

5. They practice E every day so that they can find a good job with it.

6. I have just sold the house in the city so as that I will move to the countryside.

7. She looks for different good methods of teaching in order that she can help many people become good at E.

8. Our family canceled the trip to the mountains for the weather suddenly got bad.

`AB=sqrt((1-0)^2+(0-3)^2)=  2`

`BC=sqrt((0+3)^2+(3+5)^2)=sqrt73`

`AC=sqrt((1+3)^2+(0+5)^2)=sqrt41`

``

`=> AB+AC>BC`

`AB+BC>AC`

`AC+BC>AB`

`=>A,B,C` là các đỉnh của 1 tam giác

a) `56=47+7+2`

b) `39=31+5+3`

1. There are five rooms in my house.
2. The bus station is near the new shopping centre.
3. John's computer is new.
4. The trees are in front of the house.
5. The teacher's desk is nice. 
6. That house has two bathrooms.
7. The bedroom is my favorite room.
8. Is the house behind a garden?

Đâu thể khẳng định là chỗ đấy đúng 100%?

Nếu Mary không cải thiện điểm toán, chúng ta nên tìm gia sư cho cô ấy

thì hợp hơn mà nhỉ?

You look really smart in your new school uniform!

In the afternoon students do sports in the schoolyard

In maths lessons , I bring my calculator , ruler and pen

Do you often ride your bike to school?

a) Căn thức có nghĩa `<=> 12x+18 >=0 <=> x>= -3/2`

Vậy `x>= -3/2 ` thì căn thức có nghĩa.

b) Căn thức có nghĩa `<=> 4-6x >=0 <=> x <= 2/3`

Vậy `x<= 2/3` thì căn thức có nghĩa.

c) Căn thức có nghĩa `<=>8x-36>=0 <=> x >=9/2`

Vậy `x>= 9/2` thì căn thức có nghĩa.

d) Căn thức có nghĩa `<=> 12-9x>=0 <=>x<=4/3`

Vậy `x<= 4/3` thì căn thức có nghĩa.