Lên Vietjack.com là có nha

Vì 105=21.5

ta có: A= 4⁰+4¹+4²+4³+...+4²⁴

A= 1+(4¹+4²) +(4³+4⁴)+...+(4²³+4²⁴)

A=1+4(1+4)+4³+(1+4)+...+4²³(1+4)

A= 1+5.(4+4³+...+4²³) chia 5 dư 1 nên A-1=4+4²+...+4²⁴ chia hết cho 5 (1)

lại có: A=1+(4+4²+4³)+(4⁴+4⁵+4⁶)+...+(4²²+4²³+4²⁴)

A=1+4(1+4+4²)+4⁴(1+4+4²)+...+4²²(1+4+4²)

A=1+21(4+4⁴+...+4²²) chia 21 dư 1 vậy A-1= 4+4²+4³+...+4²⁴ chia hết cho 21 (2)

Từ (1) và (2) => A -1 = 4+4²+...+4²⁴  chia hết cho 105

Vây A chia 105 dư 1

1.It is esential for them to do the homework before going to school

2.Mai is the best at English in my class

3.I am not happy when the children lie to their parents 

ko chắc lắm đâu

Thông tin là tất cả như gì con người tiếp nhận từ thế giới xung quanh ( sự việc, sự kiện,...). Thông tin đem lại sự hiểu biết cho con người.
 

1.that

2.do

3.from

4.to

5.the

Ko chắc lắm đâu nha!

6. a. Ready-made clothes aren't as expensive as tailor-made clothes.
    b. Tailor-made clothes are more expensive than ready-made clothes.
7. a. The hill is lower than my expectations. 
    b. The hill isn't as high as I thought. 
8. a. My aunt isn't as old as you think she is. 
    b. My aunt is younger than you think.
9. a. The river wasn't as shallow as he expected.
    b. The river was deeper than he expected.
10. a. The sea wasn't as smooth as I had hoped. 
      b. The sea was more turbulent than I had hoped.

\(500-\left\{5\left[409-\left(2^3^{ }.3-21\right)^2\right]+10^3\right\}:15\)\(5\)

\(=500-\left\{5\left[409-\left(8.3-21\right)^2\right]+1000\right\}:15\)

\(=500-\left\{5\left[409-\left(24-21\right)^2\right]+1000\right\}:15\)

1. Your house is further than I thought is was.

2. A train is slower than a bus.

3. This street is narrower than the next one.

4. February is colder than July.

5. Nam is more stupid than his sister