Thực hiện phép tínha) \(A = 139\frac{5}{7}:\frac{2...

D

- Hướng dẫn giải

Phương pháp giải:

+ Áp dụng thứ tự thực hiện phép tính để tính giá trị các biểu thức. 

Giải chi tiết:

a) 

\(\begin{array}{l}A = 139\frac{5}{7}:\frac{2}{3} - 138\frac{2}{7}:\sqrt {\frac{4}{9}} \\A = 139\frac{5}{7}:\frac{2}{3} - 138\frac{2}{7}:\frac{2}{3}\\A = \left( {139\frac{5}{7} - 138\frac{2}{7}} \right):\frac{2}{3}\\A = \left( {139 + \frac{5}{7} - 138 - \frac{2}{7}} \right):\frac{2}{3}\\A = \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{10}}{7}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,:\frac{2}{3}\\A = \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{10}}{7}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \times \,\frac{3}{2}\\A = \,\,\,\,\,\,\,\,\,\,\,\frac{{15}}{7}\end{array}\)              

  b) \(B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}}\)

 \(\begin{array}{l}B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}} = \frac{{{{2.6}^9} - {2^5}{{.6}^4}{{.3}^4}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^9} - {{2.2}^4}{{.3}^4}{{.6}^4}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^9} - {{2.6}^8}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^8}\left( {6 - 1} \right)}}{{{2^2}{{.6}^8}}} = \frac{5}{2}\end{array}\)

\(\begin{array}{l}c)\,\,C = \left| {97\frac{2}{3} - 125\frac{3}{5}} \right| + 97\frac{2}{5} - 125\frac{1}{3}\\C = \left| {\frac{{293}}{3} - \frac{{628}}{5}} \right| + \frac{{487}}{5} - \frac{{376}}{3}\\C = \left| {\frac{{ - 419}}{{15}}} \right| + \frac{{487}}{5} - \frac{{376}}{3}\\C = \frac{{419}}{{15}} + \frac{{487}}{5} - \frac{{376}}{3}\\C = 0.\end{array}\)

Chọn D