Cho

D

- Hướng dẫn giải

Đáp án D 

Ta có :

$$\begin{gathered} A=\frac{\left(3{\displaystyle \frac{2}{15}}+{\displaystyle \frac{1}{5}}\right):2{\displaystyle \frac{1}{2}}}{\left(5{\displaystyle \frac{3}{7}}-2{\displaystyle \frac{1}{4}}\right):4{\displaystyle \frac{43}{56}}} \\ =\frac{\left({\displaystyle \frac{47}{15}}+{\displaystyle \frac{3}{15}}\right):{\displaystyle \frac{5}{2}}}{\left({\displaystyle \frac{38}{7}}-{\displaystyle \frac{9}{4}}\right):{\displaystyle \frac{267}{56}}}=\frac{{\displaystyle \frac{50}{15}}.{\displaystyle \frac{2}{5}}}{\left({\displaystyle \frac{152}{28}}-{\displaystyle \frac{63}{28}}\right).{\displaystyle \frac{56}{267}}} \\ =\frac{{\displaystyle \frac{4}{3}}}{{\displaystyle \frac{89}{28}}.{\displaystyle \frac{56}{267}}}=\frac{{\displaystyle \frac{4}{3}}}{{\displaystyle \frac{2}{3}}}=2 \end{gathered}$$

Và $B=\frac{1,2:\left(1{\displaystyle \frac{1}{5}}.1{\displaystyle \frac{1}{4}}\right)}{0,32+{\displaystyle \frac{2}{25}}}=\frac{{\displaystyle \frac{6}{5}}:\left({\displaystyle \frac{6}{5}}.{\displaystyle \frac{5}{4}}\right)}{{\displaystyle \frac{8}{25}}+{\displaystyle \frac{2}{25}}}=\frac{{\displaystyle \frac{6}{5}}:{\displaystyle \frac{3}{2}}}{{\displaystyle \frac{10}{25}}}=\frac{{\displaystyle \frac{4}{5}}}{{\displaystyle \frac{2}{5}}}=2$

Vậy A = B.