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Cách 1:
\(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\)
\(=\dfrac{5}{9}\times\dfrac{4}{9}\)
\(=\dfrac{20}{81}\)
Cách 2:
\(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\times\dfrac{4}{9}\)
\(=\dfrac{1}{3}\times\dfrac{4}{9}+\dfrac{2}{9}\times\dfrac{4}{9}\)
\(=\dfrac{4}{27}+\dfrac{8}{81}\)
\(=\dfrac{20}{81}\)
C1: \(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\)x\(\dfrac{4}{9}\)=\(\left(\dfrac{3}{9}+\dfrac{2}{9}\right)\text{x}\dfrac{4}{9}\)=\(\dfrac{5}{9}\text{x}\dfrac{4}{9}=\dfrac{20}{81}\)
C2: \(\left(\dfrac{1}{3}+\dfrac{2}{9}\right)\)x\(\dfrac{4}{9}\)=\(\dfrac{1}{3}\text{ x}\dfrac{4}{9}+\dfrac{2}{9}\text{ x}\dfrac{4}{9}\)=\(\dfrac{4}{27}+\dfrac{8}{81}=\dfrac{12}{81}+\dfrac{8}{81}=\dfrac{20}{81}\)
10 x 10 = 100
20 x 20 = 400
1 x 1 = 1
2 x 2 = 4
~ k CHO mK NHÉ
trả lời
10 x 10=100
20 x 20=400
1 x 1 =1
2 x 2 =4
ok bạn,kb nha
\(\frac{5}{7}+y\times\frac{1}{2}=\frac{8}{7}:\frac{3}{2}\)
=> \(\frac{5}{7}+y\times\frac{1}{2}=\frac{8}{7}\times\frac{2}{3}\)
=> \(\frac{5}{7}+y\times\frac{1}{2}=\frac{16}{21}\)
=> \(y\times\frac{1}{2}=\frac{16}{21}-\frac{5}{7}=\frac{1}{21}\)
=> \(y=\frac{1}{21}:\frac{1}{2}=\frac{1}{21}\cdot2=\frac{2}{21}\)
5/7 + Y x 1/2 = 8/7 : 3/2
=> 5/7 + Y x 1/2 = 16/21
=> Y x 1/2 = 16/21 - 5/7
=> Y x 1/2 = 1/21
=> Y = 1/21 : 1/2
=> Y = 2/21
Hok tốt ^^
\(\left(1-\dfrac{1}{35}\right)\times\left(1-\dfrac{1}{36}\right)\times..\times\left(1-\dfrac{1}{2011}\right)\)
=\(\dfrac{34}{35}\times\dfrac{35}{36}\times\dfrac{36}{37}\times...\times\dfrac{2010}{2011}\)
=\(\dfrac{34}{2011}\)
Ta có ; \(1\dfrac{1}{10}.1\dfrac{1}{11}.....1\dfrac{1}{2011}.1\dfrac{1}{2012}\)
\(=\dfrac{11}{10}.\dfrac{12}{11}.....\dfrac{2012}{2011}.\dfrac{2013}{2012}\)
\(=\dfrac{2013}{10}=201,3\)
1 \(\dfrac{1}{10}\)x 1\(\dfrac{1}{11}\)x 1\(\dfrac{1}{12}\) x...x 1\(\dfrac{1}{2011}\)x 1\(\dfrac{1}{2012}\)
=\(\dfrac{11}{10}\)x \(\dfrac{12}{11}\)x \(\dfrac{13}{12}\)x \(\dfrac{2012}{2011}\)x \(\dfrac{2013}{2012}\)
\(B=\left(1-\dfrac{1}{400}\right)\times\left(1-\dfrac{1}{401}\right)\times....\times\left(1-\dfrac{1}{2010}\right)\)
\(B=\dfrac{399}{400}\times\dfrac{400}{401}\times....\times\dfrac{2009}{2010}\)
\(B=\dfrac{399}{2010}\)
Sao nhóm cuối lại là 1 + \(\dfrac{1}{2010}\) trái với quy luật thế em