Question

tính hợp lí

( -5/12 . 4/21+ 5/12. -17/21). (-2,4)

Answer 1

\(\left(\frac{-5}{12}.\frac{4}{21}+\frac{5}{12}.\frac{-17}{21}\right).\left(\frac{-2}{4}\right)\)

\(=\left(\frac{-5}{12}\left(\frac{4}{21}+\frac{17}{21}\right)\right).\left(\frac{-2}{4}\right)\)

\(=\left(\frac{-5}{12}.1\right).\left(\frac{-2}{4}\right)\)

\(=\frac{-5}{12}.\frac{-2}{4}=\frac{5}{24}\)

Answer 2

\(\left(\frac{-5}{12}.\frac{4}{21}+\frac{5}{12}.\frac{-17}{21}\right).\left(-2,4\right)\)

\(=\left[\frac{\left(-5\right)}{12}+\frac{5}{12}\right].\left[\frac{\left(-17\right)}{21}+\frac{4}{21}\right].\left(\frac{-24}{10}\right)\)

\(=0.\frac{\left(-13\right)}{21}.\frac{\left(-12\right)}{5}\)

\(=0\)