Question

Phép tính nào dưới đây là đúng?

(A) \(\frac{2}{3} + \frac{{ - 4}}{6} = \frac{{ - 2}}{6}\)

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

(C) \(\frac{2}{3} - \frac{3}{5} = \frac{1}{{15}}\)

(D) \(\frac{3}{5}:\frac{3}{{ - 5}} =  - \frac{9}{{25}}\)

Answer 1

(A) \(\frac{2}{3} + \frac{{ - 4}}{6} = \frac{4}{6} + \frac{{ - 4}}{6} = 0\) => A sai

(B) \(\frac{2}{3}.\frac{{ - 1}}{5} = \frac{{ - 2}}{{15}}\) mà \(\frac{{3 - 2}}{5} = \frac{1}{5}\) => B sai

(C) \(\frac{2}{3} - \frac{3}{5} = \frac{{10}}{{15}} - \frac{9}{{15}} = \frac{1}{{15}}\) => C đúng

(D) \(\frac{3}{5}:\frac{3}{{ - 5}} = \frac{3}{5}.\frac{{ - 5}}{3} = \frac{{ - 15}}{{15}} =  - 1\) => D sai

=> Chọn C.