\(A=\dfrac{7}{19}\cdot\dfrac{8}{11}+\dfrac{7}{11}\cdot\dfrac{3}{11}\\ =\dfrac{7\cdot8}{19\cdot11}+\dfrac{7}{11}\cdot\dfrac{3}{11}\\ =\dfrac{8}{19}\cdot\dfrac{7}{11}+\dfrac{7}{11}\cdot\dfrac{3}{11}\\ =\dfrac{7}{11}\cdot\left(\dfrac{8}{19}+\dfrac{3}{11}\right)\\ =\dfrac{7}{11}\cdot\dfrac{145}{209}\\ =\dfrac{1015}{2299}\)
= \(\dfrac{7}{19}\) . \(\dfrac{8}{11}\) + \(\dfrac{7}{11}\) . \(\dfrac{3}{11}\)
= \(\dfrac{56}{209}\) + \(\dfrac{21}{121}\)
= \(\dfrac{1015}{2299}\)
Cách 1 : \(A=\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{11}.\dfrac{3}{11}\)
= \(\dfrac{7.8}{19.11}+\dfrac{7}{11}.\dfrac{3}{11}\)
= \(\dfrac{8}{19}.\dfrac{7}{11}+\dfrac{7}{11}.\dfrac{3}{11}\)
= \(\dfrac{7}{11}.\left(\dfrac{8}{19}+\dfrac{3}{11}\right)\)
= \(\dfrac{7}{11}.\dfrac{145}{209}\)
= \(\dfrac{1015}{2299}\)
Cách 2 : \(A=\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{11}.\dfrac{3}{11}\)
= \(\dfrac{56}{209}+\dfrac{21}{121}\)
= \(\dfrac{1015}{2299}\)
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