A = \(\frac12\) x \(\frac23\) x \(\frac34\) x \(\frac45\) x ... x \(\frac{2012}{2013}\)

A = \(\frac{2\times3\times4\times\ldots\times2012}{2\times3\times4\times\ldots\times2012}\) x \(\frac{1}{2013}\)

A = 1 x \(\frac{1}{2013}\)

A = \(\frac{1}{2013}\)

`1/2xx2/3xx3/4xx4/5xx...xx2012/2013`

`=(1xx2xx3xx...xx2012)/(2xx3xx4xx...xx2013)`

`=1/2013xx(2xx3xx...xx2012)/(2xx3xx...xx2012)`

`=1/2013xx1`

`=1/2023`

Vậy: `..`

hinh nhu bn chep sai dau bai

\(\frac{17}{2}\times\frac{3}{5}+\frac{3}{5}\times\frac{1}{2}+\frac{3}{5}\)

\(=\frac{3}{5}\times\left(\frac{17}{2}+\frac{1}{2}\right)\)

\(=\frac{3}{5}\times9\)

\(=\frac{27}{5}\)

Ai Fan anh Kha diem danh

\(\frac{17}{2}\times\frac{3}{5}+\frac{3}{5}\times\frac{1}{2}+\frac{3}{5}\)

\(=\frac{3}{5}\times\left(\frac{17}{2}+\frac{1}{2}+1\right)\)

\(=\frac{3}{5}\times\left(\frac{17}{2}+\frac{1}{2}+\frac{2}{2}\right)\)

\(=\frac{3}{5}\times\frac{20}{2}\)

\(=\frac{60}{10}=6\)

CHÚC BẠN HOK TOT

\(a,\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}\)

Cách 1: \(\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}=1\times\frac{3}{7}=\frac{10}{7}\)

Cách 2: \(\left(\frac{6}{11}+\frac{5}{11}\right)\times\frac{3}{7}=\frac{6}{11}\times\frac{3}{7}+\frac{5}{11}\times\frac{3}{7}=\frac{18}{77}+\frac{15}{77}=\frac{33}{77}=\frac{3}{7}\)

\(b,\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}\)

Cách 1: \(\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}=\frac{7}{15}+\frac{2}{15}=\frac{9}{15}\)

Cách 2: \(\frac{3}{5}\times\frac{7}{9}+\frac{3}{5}\times\frac{2}{9}=\frac{3}{5}\times1=\frac{3}{5}\)

P/s: Ý B có vấn đề thì phải

\(a,\left(\frac{6}{11}+\frac{5}{11}\right)x\frac{3}{7}\)

\(=\frac{11}{11}=1x\frac{3}{7}\)

\(=\frac{3}{7}\)

cach 2 

\(\frac{6}{11}x\frac{3}{7}+\frac{5}{11}x\frac{3}{7}\)

\(=\frac{18}{77}+\frac{15}{77}\)

\(=\frac{33}{77}=\frac{3}{7}\)

\(b,\frac{3}{5}x\frac{7}{9}+\frac{3}{5}x\frac{2}{9}\)

\(=\frac{21}{45}+\frac{6}{45}\)

\(=\frac{27}{45}=\frac{3}{5}\)

cách 2 : 

\(\frac{3}{5}x\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{3}{5}x\frac{9}{9}\)

\(=\frac{27}{45}=\frac{3}{5}\)

\(3+\frac{2}{5}-\frac{3}{4}\times\frac{4}{5}\)

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

\(=\frac{3\times20+2\times4-3\times5}{20}\)

\(=\frac{60+8-15}{20}\)

\(=\frac{68-15}{20}\)

\(=\frac{53}{20}\)

\(5-\frac{7}{9}+\frac{2}{3}-\frac{5}{6}:\frac{4}{9}\)

\(=5-\frac{7}{9}+\frac{2}{3}-\frac{45}{24}\)

\(=\frac{5\times72-7\times8+2\times24-45\times3}{72}\)

\(=\frac{360-56+48-135}{72}\)

\(=\frac{217}{72}\)

Ta có: 272727x28 - 282828x27 = 27x10101x28 - 28x10101x27 = 0

Vậy, phép tính đã cho bằng 0

4) \(\frac{29x101-101}{2x19x101+4x101}\)

= \(\frac{\left(29-1\right)x101}{\left(38-4\right)x101}\)

=\(\frac{28}{34}=\frac{14}{17}\)

5) \(\left(\frac{2}{7}+\frac{11}{7}+\frac{1}{7}\right)-\frac{3}{8}-\frac{5}{8}+\frac{1}{3}\)

= \(\frac{14}{7}-\frac{8}{8}+\frac{1}{3}\)

= \(2-1+\frac{1}{3}=\frac{4}{3}\)

Nhớ tk cho mình nhé

1\(\frac{423133x846267+423134}{423133x846267+423134}=1\))

\(\frac{\left(423133+1\right)x846267-423133}{423133x846267+423134}\)

=\(\frac{423133x846267+846267-423133}{423133x846267+423134}\)

= \(\frac{423133x846267+423134}{423133x846267+423134}\)

= 1

Nhớ tk cho mình nhé (các câu sau  làm riêng cho đỡ dài

\(\frac{1}{10}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{5}\cdot\frac{5}{4}\cdot\frac{4}{3}\cdot\frac{3}{2}=\frac{1}{10}\)

\(\frac{1}{10}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times\frac{5}{6}\times\frac{6}{5}\times\frac{5}{4}\times\frac{4}{3}\times\frac{3}{2}\)\(\frac{3}{2}\)

\(=\frac{1}{10}\times\left(\frac{2}{3}\times\frac{3}{2}\right)\times\left(\frac{3}{4}\times\frac{4}{3}\right)\times\left(\frac{4}{5}\times\frac{5}{4}\right)\times\left(\frac{5}{6}\times\frac{6}{5}\right)\)

\(=\frac{1}{10}\times1\times1\times1\times1\)

\(=\frac{1}{10}\)

#Chúc bạn học tốt !

#k cho mình nhé ?

\(a,\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(=\frac{1}{2}-\frac{1}{6}=\frac{1}{3}\)

\(b,\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\)

\(=\frac{1\times2\times3}{2\times3\times4}=\frac{1}{4}\)