Question

Bài 1:Tính:

f,\(\dfrac{5}{9}\) . \(\dfrac{7}{13}\) + \(\dfrac{5}{9}\) . \(\dfrac{9}{13}\) - \(\dfrac{5}{9}\) : \(\dfrac{13}{3}\)

Answer 1

\(\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{9}{13}-\dfrac{5}{9}:\dfrac{13}{3}\\ =\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{9}{13}-\dfrac{5}{9}\cdot\dfrac{3}{13}\\ =\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{9}{13}-\dfrac{3}{13}\right)\\ =\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)

Answer 2

\(\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{9}{13}-\dfrac{5}{9}:\dfrac{13}{3}\)

\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{9}{13}-\dfrac{5}{9}\cdot\dfrac{3}{13}\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{9}{13}-\dfrac{3}{13}\right)\)

\(=\dfrac{5}{9}\cdot\left(\dfrac{7+9-3}{13}\right)\)

\(=\dfrac{5}{9}\cdot\dfrac{13}{13}\)

\(=\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)