Question

Tính 1 cách hợp lí nhất :

\(\frac{-2}{5}.\frac{4}{7}+\frac{-3}{5}.\frac{2}{7}+\frac{-3}{5}\)

Answer 1

\(\frac{-3}{5}.\frac{4}{7}+\frac{-3}{5}.\frac{2}{7}+\frac{-3}{5}\)

\(=\frac{-3}{5}.\frac{4}{7}+\frac{-3}{5}.\frac{2}{7}+\frac{-3}{5}.\frac{1}{7}\)

\(=\frac{-3}{5}\left(\frac{4}{7}+\frac{2}{7}+\frac{1}{7}\right)\)

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

\(=\frac{-3}{5}\)

Answer 2

\(-\frac{2}{5}x\frac{1}{7}+-\frac{3}{5}x\frac{2}{7}+-\frac{3}{5}=-\frac{2}{5}x\frac{1}{7}+-\frac{3}{5}\left(\frac{2}{7}+1\right)=-\frac{2}{5}x\frac{1}{7}+-\frac{3}{5}x\frac{9}{7}.\)

\(-\frac{2}{35}-\frac{27}{35}=-\frac{29}{35}\)

tôi tính nhẩm vậy ko biết có đứng ko

Answer 3

Bạn CTV viết sai đề rồi kìa.