Question

Tính hợp lý: \(\dfrac{-4}{13}\).\(\dfrac{5}{17}\)+\(\dfrac{-12}{13}\).\(\dfrac{4}{17}\)+\(\dfrac{4}{13}\)

Giúp mình với nha! Thank you.

Answer 1

\(\dfrac{-4}{13}\cdot\dfrac{5}{17}+\dfrac{-12}{13}\cdot\dfrac{4}{17}+\dfrac{4}{13}\)

\(=\dfrac{-4}{17}\cdot\dfrac{5}{17}+\dfrac{-4}{13}\cdot3\cdot\dfrac{4}{17}+\dfrac{4}{13}\)

\(=\dfrac{4}{13}\left(\dfrac{-5}{17}+\dfrac{-12}{17}+1\right)\)

\(=\dfrac{4}{13}\left(-1+1\right)=\dfrac{4}{13}\cdot0=0\)

Answer 2

\(\dfrac{-4}{13}.\dfrac{5}{14}+\dfrac{-12}{13}.\dfrac{4}{17}+\dfrac{4}{13}\)

= \(\dfrac{-4.5}{13.17}+\dfrac{-12.4}{13.17}+\dfrac{4.17}{13.17}\)

= \(\dfrac{-20-28+68}{13.17}\) = \(\dfrac{20}{221}\)