Question

34/7x13+51/13x22+85/22x37+68/37x49

 

Answer 1

Đặt A = 34/7x13 + 51/13x22 + 85/22x37 + 68/37x49

\(A=17x\left(\frac{2}{7x13}+\frac{3}{13x22}+\frac{5}{22x37}+\frac{4}{37x49}\right)\)

\(\frac{3}{17}xA=\frac{6}{7x13}+\frac{9}{13x22}+\frac{15}{22x37}+\frac{12}{37x49}\)

\(\frac{3}{17}xA=\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{22}+\frac{1}{22}-\frac{1}{37}+\frac{1}{37}-\frac{1}{49}\)

\(\frac{3}{17}xA=\frac{1}{7}-\frac{1}{49}\)

\(\frac{3}{17}xA=\frac{6}{49}\)

\(A=\frac{6}{49}:\frac{3}{17}\)

\(A=\frac{6}{49}x\frac{17}{3}=\frac{34}{49}\)