Question

Tính nhanh:

A:= \(\dfrac{-3}{5}\). \(\dfrac{3}{13}\)+\(\dfrac{-3}{5}\).\(\dfrac{10}{13}+5\)

B:= \(\dfrac{31}{23}.\left(\dfrac{7}{31}+\dfrac{8}{23}\right)\)

Answer 1

\(A=\dfrac{-3}{5}.\dfrac{3}{13}+\dfrac{-3}{5}.\dfrac{10}{13}+5\)

\(A=\dfrac{-3}{5}\left(\dfrac{3}{13}+\dfrac{10}{13}\right)+5\)

\(A=\dfrac{-3}{5}.1+5\)

\(A=\dfrac{-3}{5}+5\)

\(A=\dfrac{22}{5}\)

Answer 2

A = \(\dfrac{-3}{5}.\dfrac{3}{13}+\dfrac{-3}{5}.\dfrac{10}{13}+5\)

A = \(\dfrac{-3}{5}.\left(\dfrac{3}{13}+\dfrac{10}{13}\right)+5\)

A = \(\dfrac{-3}{5}.1+5\)

A = \(\dfrac{-3}{5}+5\)

A = \(\dfrac{-3}{5}+\dfrac{25}{5}\)

A = \(\dfrac{22}{5}\)

Answer 3

\(B=\dfrac{31}{23}.\left(\dfrac{7}{31}+\dfrac{8}{23}\right)\)

\(B=\dfrac{31}{23}.\dfrac{7}{31}+\dfrac{31}{23}.\dfrac{8}{23}\)

\(B=\dfrac{7}{23}+\dfrac{248}{529}\)

\(B=\dfrac{409}{529}\)

Mình không tìm thấy quy luật nào cả...