a: \(=\dfrac{3}{7}\cdot\dfrac{7}{3}\cdot\dfrac{6}{13}\cdot\dfrac{13}{6}=1\)
b: \(=\dfrac{2}{5}\cdot\dfrac{3}{4}\cdot\dfrac{5}{2}\cdot\dfrac{8}{3}=\dfrac{2}{2}\cdot\dfrac{5}{5}\cdot\dfrac{3}{3}\cdot\dfrac{8}{4}=2\)
c: \(=\dfrac{17}{35}\cdot\dfrac{21}{45}\cdot\dfrac{7}{17}\cdot\dfrac{3}{7}\)
\(=\dfrac{17}{17}\cdot\dfrac{7}{7}\cdot\dfrac{21}{35}\cdot\dfrac{3}{45}=\dfrac{3}{5}\cdot\dfrac{1}{15}=\dfrac{1}{25}\)
3/7 x 6/13 x 13/6 x 7/3= (3/7 x 7/3) x (6/13 x 13/6)
= 1/1 x 1/1
= 1/1=1
6/15 x 3/4 x 30/12 x 8/3=(6/15 x 30/12) x (3/4 x 8/3)
= 2/2 x 1/2
= 1 x 1/2
= 1/2
17/ 35 x 21/45 x 7/17 x 9/21= (17/35 x 7/17) x (21/45 x 9/21)
= 1/5 x 1/5
= 1/25
\(\dfrac{3}{7}\times\dfrac{6}{13}\times\dfrac{13}{6}\times\dfrac{7}{3}.\\ =\left(\dfrac{6}{13}\times\dfrac{13}{6}\right)\times\left(\dfrac{3}{7}\times\dfrac{7}{3}\right).\\ =1\times1=1.\\ \dfrac{6}{15}\times\dfrac{3}{4}\times\dfrac{30}{12}\times\dfrac{8}{3}.\\ =\dfrac{2}{5}\times\dfrac{3}{4}\times\dfrac{5}{2}\times\dfrac{8}{3}.\\ =\left(\dfrac{2}{5}\times\dfrac{5}{2}\right)\times\left(\dfrac{3}{4}\times\dfrac{8}{3}\right).\\ =1\times2=2.\\ \dfrac{17}{35}\times\dfrac{21}{45}\times\dfrac{7}{17}\times\dfrac{9}{21}.\\ =\left(\dfrac{17}{35}\times\dfrac{7}{17}\right)\times\left(\dfrac{21}{45}\times\dfrac{9}{21}\right).\\ =\dfrac{1}{5}\times\dfrac{1}{5}=\dfrac{1}{25}.\)
