Question

Tính nhanh : \(\frac{-2}{5}\). (\(\frac{5}{17}\)- \(\frac{9}{15}\)) - \(\frac{-2}{5}\). (\(\frac{2}{17}\)+ \(\frac{-2}{5}\)).

Nhớ tính cụ thể ra nhé , ai đúng mình tick , nhanh chân lên mọi người , mình gấp lắm rồi.

Answer 1

\(\frac{-2}{5}.\left(\frac{5}{17}-\frac{9}{15}\right)-\frac{-2}{5}.\left(\frac{2}{17}+\frac{-2}{5}\right)\)

\(=\frac{-2}{5}.\frac{5}{17}-\frac{-2}{5}.\frac{3}{5}-\frac{-2}{5}.\frac{2}{17}-\frac{-2}{5}.\frac{-2}{5}\)

\(=\frac{-2}{5}.\left(\frac{5}{17}-\frac{2}{17}\right)-\frac{-2}{5}.\left(\frac{3}{5}+\frac{-2}{5}\right)\)

\(=\frac{-2}{5}.\frac{3}{17}-\frac{-2}{5}.\frac{1}{5}\)

\(=\frac{-2}{5}.\left(\frac{3}{17}-\frac{1}{5}\right)\)

\(=\frac{-2}{5}.\frac{-2}{85}\)

\(=\frac{4}{425}\)

Answer 2

\(\frac{-2}{5}.\left(\frac{5}{17}-\frac{9}{15}\right)-\frac{-2}{5}.\left(\frac{2}{17}+\frac{-2}{5}\right)\)

= \(\frac{-2}{5}.\frac{-26}{85}-\frac{-2}{5}.\frac{-24}{85}\)

= \(\frac{-2}{5}.\left(\frac{-26}{85}-\frac{-24}{85}\right)\)

= \(\frac{-2}{5}.\frac{-2}{85}\)

= \(\frac{4}{425}\)