Question

4. Tính hợp lí :

\(\dfrac{5}{13}\) . \(\dfrac{8}{15}\) + \(\dfrac{5}{13}\) . \(\dfrac{26}{15}\) - \(\dfrac{5}{13}\) . \(\dfrac{8}{15}\)

Answer 1

\(\dfrac{5}{13}.\dfrac{8}{15}+\dfrac{5}{13}.\dfrac{26}{15}-\dfrac{5}{13}.\dfrac{8}{15}.\\ =\dfrac{5}{13}.\left(\dfrac{8}{15}+\dfrac{26}{15}-\dfrac{8}{15}\right).\\ =\dfrac{5}{13}.\dfrac{26}{15}=\dfrac{2}{3}.\)

Answer 2

Answer 3

\(\dfrac{5}{13}\times\dfrac{8}{15}+\dfrac{5}{13}\times\dfrac{26}{15}-\dfrac{5}{13}\times\dfrac{8}{15}\)

\(=\dfrac{5}{13}\times\left(\dfrac{8}{15}+\dfrac{26}{15}-\dfrac{8}{15}\right)\)

\(=\dfrac{5}{13}\times\dfrac{26}{15}\)

\(\dfrac{2}{3}\)