kết quả =4

= 2 + 2 + 2 + 2 + 1 + 1 + 1 + 1 - 2 -2 -2 -2 = 4  nha = ))

bằng 4 k cho mk nhé!!!

Đặt A = \(\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{10}}\)

Nhân cả hai với 2 ta được :

2A = \(2\left(\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{10}}\right)\)

=> 2A = \(1+\frac{1}{2^1}+\frac{1}{2^2}+...+\frac{1}{2^9}\)

Trừ 2A cho A , ta được :

2A - A = \(\left(1+\frac{1}{2^1}+\frac{1}{2^2}+...+\frac{1}{2^9}\right)-\left(\frac{1}{2^1}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{10}}\right)\)

=> A = \(1-\frac{1}{2^{10}}\)

A=1/2+1/2^2+1/2^3+.............+1/2^10

2A=1+1/2+1/2^2+.............+1/2^9

2a-a=(1/2+1/2^2+1/2^3.....+1/2^10)-(1+1/2+1/2^2............+1/2^9)

=>a=1-1/2^10

=>a=1-1/1024

=>A=1023/1024

 = -1/2.(-2/3).(-3/4). .... .(-99/100)

 = -(1/2.2/3. .... . 99/100)

 = -(1.2.3. .... . 99/2.3.4. .... . 100)

 = -1/100

Tk mk nha

toán lớp mấy vậy

 6

nhanh len to dang can gap lam

\(=\dfrac{8\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)}{2}-\dfrac{3^{16}}{2}\)

\(=\dfrac{\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)-3^{16}}{2}\)

\(=\dfrac{\left(3^8-1\right)\left(3^8+1\right)-3^{16}}{2}\)

=-1/2

nhân cả cụm đó với 2 rồi trừ đi cụm ban đầu thì còn là -2-1/1024 =-2049/1024

nhanh nhanh nhanh

Ta có:\(M=1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^9}\)

\(2M=2+1+\dfrac{1}{2}+...+\dfrac{1}{2^8}\)

\(2M-M=\left(2+1+\dfrac{1}{2}+...+\dfrac{1}{2^8}\right)-\left(1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^9}\right)\)

\(M=2-\dfrac{1}{2^9}\)

\(M=\dfrac{1023}{512}\)

1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6

= 1/1-1/6

=6/6-1/6

= 5/6

=5/6 nhé.

chúc Phạm Quốc Cường học tốt nhé

1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 -1/6

= 1/1 - 1/6

= 5/6