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

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

\(\dfrac{3}{17}A=\dfrac{1}{7}-\dfrac{1}{49}=\dfrac{6}{49}\)

\(A=\dfrac{6}{49}:\dfrac{3}{17}=\dfrac{6.17}{49.3}=\dfrac{34}{49}\)

bạn viết sai đề rồi phải là 26/43.49 mới đúng rồi làm thế này

A=34/7.13+51/13.22+85/22.37+68/37.49

=17(2/7.13+3/13.22+5/22.37+4/37.49)

=17/3(6/7.13+9/13.22+15/22.37+12/37.49)

=17/3(1/7-1/13+1/13-1/22+1/22-1/37+1/37-1/49)=17/3(1/7-1/49)

b=13(3/7.16+5/16.31+4/31.43+2/43.49)

b=13/3(9/7.16+15/16.31+12/31.43+6/43.49)

=13/3(1/7-1/16+1/16-1/31+1/31-1/43+1/43-1/49)=13/3(1/7-1/49)

=>A/B=17/3/13/3=17/13

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