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13 tháng 8 2017

\(M=\dfrac{26}{7.11}+\dfrac{65}{11.21}+\dfrac{39}{21.27}+\dfrac{143}{27.49}\)

\(M=\dfrac{13.2}{7.11}+\dfrac{13.5}{11.21}+\dfrac{13.3}{21.27}+\dfrac{13.11}{27.49}\)

\(M=13.\dfrac{2}{7.11}+13.\dfrac{5}{11.21}+13.\dfrac{3}{21.27}+13.\dfrac{11}{27.49}\)

\(M=13.\left(\dfrac{2}{7.11}+\dfrac{5}{11.21}+\dfrac{3}{21.27}+\dfrac{11}{27.49}\right)\)

\(M=13.\dfrac{1}{2}\left(\dfrac{4}{7.11}+\dfrac{10}{11.21}+\dfrac{6}{21.27}+\dfrac{22}{27.49}\right)\)

\(M=\dfrac{13}{2}\left(\dfrac{1}{7}-\dfrac{1}{49}\right)\)

\(M=\dfrac{13}{2}.\dfrac{6}{49}=\dfrac{39}{49}\)

N sai đề rồi chuyển 35 thành 85 tính tương tự xong lấy \(P=\dfrac{M}{N}+\dfrac{34}{29}\)

P=2

7 tháng 8 2017

M=26/7x11+65/11x21+39/21x27+143/37x49

M=26/77+65/231+13/189+143/1813

M=0,766705481

N=51/7x16+17/16x19+35/19x34+85/34x49

N=51/112+17/304+35/646+5/98

N=0,6164781702

P=0,766705481/0,6164781702+29/34

P=2,096627519

7 tháng 8 2017

p=2,316988801

24 tháng 3 2017

Ta có :

\(A=\dfrac{34}{7.13}+\dfrac{51}{13.22}+\dfrac{85}{22.37}+\dfrac{68}{37.49}\)

\(\dfrac{A}{17}=\dfrac{2}{7.13}+\dfrac{3}{13.22}+\dfrac{5}{22.37}+\dfrac{4}{37.49}\)

\(A.\dfrac{3}{17}=\dfrac{6}{7.13}+\dfrac{9}{13.22}+\dfrac{15}{22.37}+\dfrac{12}{37.49}\)

\(A.\dfrac{3}{17}=\dfrac{1}{7}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{22}+\dfrac{1}{22}-\dfrac{1}{37}+\dfrac{1}{37}-\dfrac{1}{49}\)

\(A.\dfrac{3}{17}=\dfrac{1}{7}-\dfrac{1}{49}\)

\(A.\dfrac{3}{17}=\dfrac{6}{49}\)

\(\Rightarrow A=\dfrac{6}{49}:\dfrac{3}{17}=\dfrac{34}{49}\)

\(B=\dfrac{39}{7.16}+\dfrac{65}{16.31}+\dfrac{52}{31.43}+\dfrac{26}{37.49}\)

\(\dfrac{B}{13}=\dfrac{3}{7.16}+\dfrac{5}{16.31}+\dfrac{4}{31.43}+\dfrac{2}{37.49}\)

\(B.\dfrac{3}{13}=\dfrac{9}{7.16}+\dfrac{15}{16.31}+\dfrac{12}{31.43}+\dfrac{6}{43.49}\)

\(B.\dfrac{3}{13}=\dfrac{1}{7}-\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{31}+\dfrac{1}{31}-\dfrac{1}{43}+\dfrac{1}{43}-\dfrac{1}{49}\)

\(B.\dfrac{3}{13}=\dfrac{1}{7}-\dfrac{1}{49}\)

\(B.\dfrac{3}{13}=\dfrac{1}{7}-\dfrac{1}{49}=\dfrac{6}{49}\)

\(\Rightarrow B=\dfrac{6}{49}:\dfrac{3}{13}=\dfrac{26}{49}\)

\(\Rightarrow\dfrac{A}{B}=\dfrac{34}{49}:\dfrac{26}{49}=\dfrac{17}{13}\)

Chúc bn học tốt!!!!!!!!!

24 tháng 3 2017

Cảm ơn bn nhìu nha!!!!!!!!!

6 tháng 4 2017

Link này bạn: Câu hỏi của Quỳnh Anh Shuy - Toán lớp 7 | Học trực tuyến

1 tháng 4 2017

\(\dfrac{\Leftrightarrow3A}{17}=\left(\dfrac{6}{7.13}+\dfrac{9}{13.22}+\dfrac{15}{22.37}+\dfrac{12}{37.49}+\dfrac{30}{49.79}+\dfrac{47}{79.126}\right)x=\dfrac{289}{9}\)

1 tháng 4 2017

chết ấn nhầm nút

16 tháng 2 2022

\(a,\dfrac{x}{4}=\dfrac{15}{20}\\ \Rightarrow\dfrac{x}{4}=\dfrac{3}{4}\\ \Rightarrow x=3\\ b,\dfrac{15}{x}=\dfrac{25}{35}\\ \Rightarrow\dfrac{15}{x}=\dfrac{5}{7}\\ \Rightarrow\dfrac{15}{x}=\dfrac{15}{21}\\ \Rightarrow x=21\\ c,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\\ d,\dfrac{3}{x}=\dfrac{51}{85}\\ \Rightarrow\dfrac{3}{x}=\dfrac{3}{5}\\ \Rightarrow x=5\)

19 tháng 3 2022

a,x4=1520x4=34x=3b,15x=253515x=5715x=1521x=21c,x5=2665x5=25x=2d,3x=51853x=35x=5

\(M=\dfrac{6}{10.13}+\dfrac{6}{13.16}+\dfrac{6}{16.19}+\dfrac{6}{19.21}\)

\(\dfrac{1}{2}M=\dfrac{3}{10.13}+\dfrac{3}{13.16}+\dfrac{3}{16.19}+\dfrac{3}{19.21}\)

\(\dfrac{1}{6}M=\dfrac{1}{10}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{21}\)

\(\dfrac{1}{6}M=\dfrac{1}{10}-\dfrac{1}{21}\)

\(M=\dfrac{11}{210}:\dfrac{1}{6}=\dfrac{11}{35}\)

\(N=\dfrac{1}{20}-\dfrac{1}{23}+\dfrac{1}{23}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{29}+\dfrac{1}{29}-\dfrac{1}{30}\)

\(=\dfrac{1}{20}-\dfrac{1}{30}\)

\(=\dfrac{1}{60}\)

 

\(\dfrac{M}{N}=\dfrac{11}{35}:\dfrac{1}{60}=\dfrac{132}{7}\)\(\dfrac{132}{25}\)