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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 ^^
1−199 x 1 − 1100....1−120061-199 � 1 - 1100....1-12006
=(9999−1999999-199)x(100100−1100100100-1100)....(20062006−1200620062006-12006) = 9899x99100....20052006=982006
NÈ EM
( 1 - 1 / 2 ) x ( 1 - 1 / 3 ) x K x (1 - 1 / 2019 ) x (1 - 1 / 2020 )
Chỗ chứ K đấy tớ thay bằng ... nhé
( 1 - \(\frac{1}{2}\) ) x ( 1 - \(\frac{1}{3}\) ) x ... x ( 1 - \(\frac{1}{2019}\) ) x ( 1 - \(\frac{1}{2020}\) )
= ( \(\frac{2}{2}\) - \(\frac{1}{2}\) ) x ( \(\frac{3}{3}\) - \(\frac{1}{3}\) ) x...x ( \(\frac{2019}{2019}\) - \(\frac{1}{2019}\) ) x ( \(\frac{2020}{2020}\) - \(\frac{1}{2020}\) )
= \(\frac{1}{2}\) x \(\frac{2}{3}\) x...x \(\frac{2018}{2019}\) x \(\frac{2019}{2020}\)
= \(\frac{1.2....2018.1019}{2.3.....2019.2020}\)
= \(\frac{1}{2020}\)
Học tốt !
\(B=\left(1-\dfrac{1}{400}\right)\times\left(1-\dfrac{1}{401}\right)\times....\times\left(1-\dfrac{1}{2010}\right)\)
\(B=\dfrac{399}{400}\times\dfrac{400}{401}\times....\times\dfrac{2009}{2010}\)
\(B=\dfrac{399}{2010}\)
Sao nhóm cuối lại là 1 + \(\dfrac{1}{2010}\) trái với quy luật thế em