Question

[Ngân Thiên]

\(\dfrac{1}{7}\).\(\dfrac{-3}{8}\)+\(\dfrac{-13}{8}\).\(\dfrac{-13}{7}\)

Answer 1

[Nguyễn Lê Phước Thịnh]

\(=\dfrac{-1\cdot3+13\cdot13}{56}=\dfrac{169-1}{56}=\dfrac{168}{56}=3\)