Question

Tính hợp lí:

\(-(\dfrac35+\dfrac34)-(-\dfrac34+\dfrac25)\)

Answer 1

\(-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(-\dfrac{3}{4}+\dfrac{2}{5}\right)\)

\(=\dfrac{-3}{5}-\dfrac{3}{4}+\dfrac{3}{4}-\dfrac{2}{5}\)

\(=\left(\dfrac{-3}{5}-\dfrac{2}{5}\right)+\left(\dfrac{-3}{4}+\dfrac{3}{4}\right)\)

\(=\left(-1\right)+0\)

\(=-1.\)

Answer 2

\(-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(\dfrac{-3}{4}+\dfrac{2}{5}\right)=\dfrac{-3}{5}-\dfrac{3}{4}+\dfrac{3}{4}-\dfrac{2}{5}\)

\(=\left(\dfrac{-3}{5}-\dfrac{2}{5}\right)+\left(\dfrac{-3}{4}+\dfrac{3}{4}\right)=-1+0=-1\)