A= 2 3/13 x 13/58 x 8 x2 15/24 x 8/ 21 Đây là dạng hỗn số, nhanh giúp mình với mình đang vội
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Chị ơi tìm gì đấy ạ chị noi thế có bố em cũng chả giải được
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\(=\dfrac{29}{13}\cdot\dfrac{13}{29}\cdot4\cdot\dfrac{21}{8}\cdot\dfrac{8}{21}=4\)
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ta có:
\(1+\frac{1}{4}+\frac{1}{28}+\frac{1}{70}+...+\frac{1}{x\left(x+3\right)}\)=1\(\frac{7}{24}\)\(=\frac{31}{24}\)
\(1+\frac{1}{1.4}+\frac{1}{4.7}+...+\frac{1}{x\left(x+3\right)}=\frac{31}{24}\)
\(3+\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{x\left(x+3\right)}=\frac{31}{3}\)
\(3+1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{x}-\frac{1}{x+3}=\frac{31}{3}\)
\(3+1-\frac{1}{x+3}=\frac{31}{3}\)
\(4-\frac{1}{x+3}=\frac{31}{3}\)
\(\frac{1}{x+3}=4-\frac{31}{3}=\frac{-19}{3}\)
=>ko tìm được x
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a) ( 72 - 8 x 9 ) : ( 20 + 21 + 22 + 23 + 24 + 25 )
= ( 72 - 72 ) : ( 20 + 21 + 22 + 23 + 24 + 25 )
= 0 : ( 20 + 21 + 22 + 23 + 24 + 25 )
= 0
b) ( 500 x 9 - 250 x 18 ) x ( 1 + 2 + 3 + ... + 9 )
= ( 500 x 9 - 250 x 2 x 9 ) x ( 1 + 2 + 3 + ... + 9 )
= ( 500 x 9 - 500 x 9 ) x ( 1 + 2 + 3 + ... + 9 )
= 0 x ( 1 + 2 + 3 + ... + 9 )
= 0
\(A=2\dfrac{3}{13}\times\dfrac{13}{58}\times8\times2\dfrac{15}{24}\times\dfrac{8}{21}\)
\(A=\dfrac{29}{13}\times\dfrac{13}{58}\times8\times\dfrac{21}{8}\times\dfrac{8}{21}\)
\(A=\dfrac{29\times13\times8\times21\times8}{13\times58\times8\times21}\)
\(A=\dfrac{1\times1\times1\times1\times8}{1\times2\times1\times1}\)
\(A=\dfrac{8}{2}\)
\(A=4\)
\(A=\dfrac{29}{13}\cdot\dfrac{13}{58}\cdot8\cdot\dfrac{21}{8}\cdot\dfrac{8}{21}=\dfrac{1}{2}\cdot8=4\)