=-(0,1+0,01+0,001+0,0001+0,00001)

=-0,11111

Đây là cách đơn giản nhất 

=-(0,1+0,01+0,001+0,0001+0,000001)

=-0,111101

Mk nhầm nha 

B = \(-\frac{1}{10}-\frac{1}{100}-\frac{1}{1000}-...-\frac{1}{1000000}\)

B = \(-\left(\frac{1}{10}+\frac{1}{10^2}+\frac{1}{10^3}+...+\frac{1}{10^6}\right)\)

Đặt A = \(\frac{1}{10}+\frac{1}{10^2}+\frac{1}{10^3}+...+\frac{1}{10^6}\)

10A = \(1+\frac{1}{10}+\frac{1}{10^2}+...+\frac{1}{10^5}\)

9A = 10A - A = \(1-\frac{1}{10^6}\)

=> A = \(\frac{1-\frac{1}{10^6}}{9}\)

=> B = \(-\left(\frac{1-\frac{1}{10^6}}{9}\right)\)

C=(0,1+0,01+0,001+...+0,000001)=-0,111111

mình ko chép đề bài

tao không biết

B = (1 + 1/2)(1 + 1/3)(1 + 1/4) ...(1 + 1/100)

    = \(\frac{3}{2}.\frac{4}{3}.\frac{5}{4}...\frac{101}{100}\)

    = \(\frac{3.4.5....101}{2.3.4...100}=\frac{101}{2}\)

C = \(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)....\left(1-\frac{1}{1000}\right)\)

   \(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}....\frac{999}{1000}\)

    \(=\frac{1.2.3...999}{2.3.4....1000}=\frac{1}{1000}\)

-0,211111

10C=1-1/10-1/100-1/1000-1/10000-1/100000

10C-C=(1-1/10-1/100-1/1000-1/10000-1/100000)-(1/10-1/100-1/1000-1/10000-1/100000-1/000000)

9C=1-1/10-1/10+1/1000000=800001/1000000

C=800001/1000000:9=88889/1000000

rtrrgryhyghry5yhyryry4

88889/1000000=0.088889

1111111

tik mk nha bạn!

111111

11111**** 100% luôn cậu tích cho tớ nhé