1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 = 10 

= 1 x 10

= 10

ai thấy đúng bấm !

= 10
Ủng hộ nha !

\(\left(1-\dfrac{1}{2}\right)\times\left(1-\dfrac{1}{3}\right)\times\left(1-\dfrac{1}{4}\right)\times...\times\left(1-\dfrac{1}{100}\right)\)

\(=\left(\dfrac{2}{2}-\dfrac{1}{2}\right)\times\left(\dfrac{3}{3}-\dfrac{1}{3}\right)\times\left(\dfrac{4}{4}-\dfrac{1}{4}\right)\times...\times\left(\dfrac{100}{100}-\dfrac{1}{100}\right)\)

\(=\dfrac{1}{2}\times\dfrac{2}{3}\times\dfrac{3}{4}\times...\times\dfrac{98}{99}\times\dfrac{99}{100}\)

\(=\dfrac{1\times2\times3\times...\times98\times99}{2\times3\times4\times...\times99\times100}\)

\(=\dfrac{1}{100}\)

\(\left(1-\dfrac{1}{2}\right)x\left(1-\dfrac{1}{3}\right)x\left(1-\dfrac{1}{4}\right)x\left(1-\dfrac{1}{5}\right)x...x\left(1-\dfrac{1}{99}\right)x\left(1-\dfrac{1}{100}\right)\)

= \(\dfrac{1}{2}x\dfrac{2}{3}x\dfrac{3}{4}x\dfrac{4}{5}x...x\dfrac{98}{99}x\dfrac{99}{100}\) = \(\dfrac{1}{100}\)

1+1+11+11+1+1+1+1+1+1+1+1+1+111+1+1+1+1+1+1+1+1+1+1111+1+1+1+11+1+1+1+1+1+1+1+1+1+1=1288

= 1288 nhé !!!

+11+11+111++1111++11

= ( 1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1) + ( 11+11+11) + 111 + 1111

= ( 1 x 33 ) + ( 11 x 3 ) + 111 + 1111

= 33 + 33 + 111 + 1111

= ( 33 + 33 ) + ( 111 + 1111 )

= 66 + 1222

= 1288

Chúc bạn học tốt !!!

a) 1/2

b) 3/8

~~~~~~~~~hok tốt~~~~~~~~~~~~

A/ \(\frac{1}{2}\)

B/ \(\frac{3}{8}\)  

= 1 số tự nhiên nào đó

mk lười tính

bằng 0

100% đúng luôn

k cho mik nha k nhiều nha 

Ko 

Đăng

Câu 

Hỏi 

Linh

Tinh

Trên 

Diễn 

Đàn

bài 1 tính nhanh

mik xin sửa đề câu a thành thế này ~

\(a,\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)

đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\)

 \(A\cdot2=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\) 

\(A\cdot2-A=\) (  \(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}\) )  - (  \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}+\frac{1}{256}\) )

\(A=1-\frac{1}{256}\)

\(A=\frac{255}{256}\)

\(b,\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)

đặt \(B=\) \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\) 

     \(B\cdot3=1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)

\(B\cdot3-B=\)  ( \(1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}\)) - \(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\) ) 

\(B\cdot2=\) \(1-\frac{1}{729}\)

\(B\cdot2=\frac{728}{729}\)

\(B=\frac{728}{729}:2\)

\(B=\frac{364}{729}\) 

\(c,\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)

ĐẶT \(C=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}\)

    \(C=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}\)

\(C=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(C=\frac{1}{1}-\frac{1}{6}\)

\(C=\frac{5}{6}\)

Cảm ơn bạn nhé

1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1

= 1 x 10

= 10

Ủng hộ nha!!!

=10, tk mk nhe

= 10 nhớ k mk đấy nha

1 + 1 + 1 + 1 + 1  + 1 + 1 + 1 + 1 + 1 = 1 x 10 = 100

tchs mình tchs lại

Tổng trên là :

\(1+1+1+1+1+1+1+1+1+1=1.10=10\)

Đáp số : 10

số đó là

1x10

=10

ai muốn thì k tui đã