2S= 2.(2+2^2+2^3+.....+2^99+2^100+2^101

=2^2+2^3+...+2^102

2s-s=(2^2+2^3+2^4+...+2^102)- (2+2^2+2^3+...+2^101)

s=2^2+2^3+2^4+...+2^102-2-2^2-2^3-...-2^101

  =2^102-2

  =2.(2^101-1)

vì .........

vậy ..........

tự bạn làm tiếp nhé

1 + 1 x 2 + 3 x 6 x 5 + 1

= 1 + 2 + 90 + 1

= 94

1 + 1 x 2 + 3 x 6 x 5 + 1

= 1 + 2 + 18 x 5 + 1

= 1 + 2 + 90 + 1

= 3 + 91 

= 94

Đưa tổng sau về thành tích :

\(a,2^3+2^5+2^6=2^3.\left(1+2^2+2^3\right)\)

\(b,x^2+x^4+x^5=x^2.\left(1+x^2+x^3\right)\)

When finding somewhere to escape from the hustle and bustle of life, my bedroom is always an ideal place. My bedroom is on the second floor. It is not exactly a large room but it is spacious enough to become my private world. It is a fully-furnished room with a single bed on the left and a wardrobe on the right corner. And there stands a wood table with a shelf that contains many interesting books and is decorated with lots of souvenirs and birthday gifts on the left corner. With two small windows on the two sides of the room, I use bright color tone for the wall to make my bedroom airier and warmer. My childhood memories is coupled with every corner of the room. In my deep thoughts, it is not only a place where greets me after strained long hours at work, brings me sweet dreams but also a friend that witnesses maturity in every step of my daily life. My bedroom- a small room but unintentionally becomes a vital piece in my whole life.

 

ko phải căn phòng kinh dị viết cho NICk mà

a.Số bút trong mỗi hộp là ước chung của 28 và 36

Vì số bút trong mỗi hộp > 2

Nên nó bằng 4

b.Mai mua số hộp là: 28:4=7 hôp

Lan mua số hộp là: 36:4=9 hộp

Đáp số: a.4 hộp

             b: Lan:9 hộp

                 Mai:7 hộp

• a)theo đề ta có:

\(2a=2.\left(2+2^2+...+2^{10}\right)\)

\(2a=2^2+2^3+...+2^{11}\)

\(2a-a=\left(2^2+2^3+...+2^{11}\right)-\left(2+2^2+...+2^{10}\right)\)

\(a=2^{11}-2\)

bài còn lại tương tự nhân 3b lên nha :)

bn xem nếu cơ số bằng bao nhiêu thì cứ nhân lên bấy nhiêu

ví dụ nếu: c=4+4^2+...+4^50

thì bn nhân 4c sau đó trừ 4 đc 3c sau đó chia 3 nữa đó

\(a=2+2^2+2^3+.....+2^{10}.\)

\(\Rightarrow2a=2^2+2^3+2^4+.....+2^{11}\)

\(\Rightarrow2a-a=\left(2^2+2^3+2^4+.....+2^{11}\right)-\left(2^1+2^2+2^3+.....+2^{10}\right)\)

\(\Rightarrow a=2^{11}-2\)

\(b=3^2+3^3+3^4+.......+3^{14}+3^{15}\)

\(\Rightarrow3b=3^3+3^4+3^5+....+3^{16}\)

\(\Rightarrow3b-b=\left(3^3+3^4+3^5+....+3^{16}\right)-\left(3^2+3^3+3^4+.......+3^{14}+3^{15}\right)\)

\(2b=3^{16}-3^2\)

\(b=\frac{3^{16}-3^2}{2}\)

a) 6

b) 1

c) 3

d) 1

a) 128 - 3(x + 4) = 23

             3(x + 4) = 128 -23

             3(x + 4) = 105

                x + 4  = 105 : 3

                x + 4  = 35

                x        = 35 - 4

                x        = 31

\(a.128-3\left(x+4\right)=23.\)

\(3\left(x+4\right)=128-23\)

\(3\left(x+4\right)=105\)

\(x+4=105:3=35\)

\(x=35-4=31\)

\(b.\left[\left(4x+28\right)\cdot3+55\right]:5=35\)

\(\left(4x+28\right)\cdot3+55=35\cdot5=175\)

\(\left(4x+28\right)\cdot3=175-55=120\)

\(4x+28=120:3=40\)

\(4x=40-28=12\)

\(x=12:4=3\)

khỏi cần nữa tao bt làm r làm cũng k k đâu

1+1=2 :)

2 ko kb

tích nha