Question

[Phạm Ngọc Đức Tân]

1. Thucự hiện phép tính một cách hợp lí :
a, 1/7 . -3/7 + 1/7 . -13/8 
b, 3/5 . 13/46 - 1/10 . 16/23
giups e vs ạ

Answer 1

[Member lỗi thời :>>]

\(\text{Phần a nên sửa đề thế này :}\) \(\frac{1}{7}.\frac{-3}{8}+\frac{1}{7}.\frac{-13}{8}\)

\(\text{Giải :}\)

\(\frac{1}{7}.\frac{-3}{8}+\frac{1}{7}.\frac{-13}{8}\)

\(=\frac{1}{7}\left(\frac{-3}{8}+\frac{-13}{8}\right)\)

\(=\frac{1}{7}.\left(-2\right)\)

\(=\frac{-2}{7}\)

Answer 2

[Member lỗi thời :>>]

\(\frac{3}{5}.\frac{13}{46}-\frac{1}{10}.\frac{16}{23}\)

\(=\frac{3}{5}.\left(\frac{1}{46}.13\right)-\frac{1}{10}.\frac{32}{46}\)

\(=\left(\frac{3}{5}.13\right).\frac{1}{46}-\left(\frac{1}{10}.32\right).\frac{1}{46}\)

\(=\frac{39}{5}.\frac{1}{46}-\frac{32}{10}.\frac{1}{46}\)

\(=\frac{78}{10}.\frac{1}{46}-\frac{32}{10}.\frac{1}{46}\)

\(=\left(\frac{78}{10}-\frac{32}{10}\right).\frac{1}{46}\)

\(=\frac{46}{10}.\frac{1}{46}\)

\(=\frac{1}{10}\)