Thực hiện phép tính
a) \(A = 139\frac{5}{7}:\frac{2}{3} - 138\frac{2}{7}:\sqrt {\frac{4}{9}} \)
b) \(B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}}\)
c) \(C = \left| {97\frac{2}{3} - 125\frac{3}{5}} \right| + 97\frac{2}{5} - 125\frac{1}{3}\)
Câu 221204: Thực hiện phép tính
a) \(A = 139\frac{5}{7}:\frac{2}{3} - 138\frac{2}{7}:\sqrt {\frac{4}{9}} \)
b) \(B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}}\)
c) \(C = \left| {97\frac{2}{3} - 125\frac{3}{5}} \right| + 97\frac{2}{5} - 125\frac{1}{3}\)
A. \(\begin{array}{l}a)\,\frac{{15}}{7}\\b)\,4\\c)\,0\end{array}\)
B. \(\begin{array}{l}a)\,\frac{{15}}{7}\\b)\,5\\c)\,1\end{array}\)
C. \(\begin{array}{l}a)\,\frac{{10}}{7}\\b)\,5\\c)\,0\end{array}\)
D. \(\begin{array}{l}a)\,\frac{{15}}{7}\\b)\,\frac{5}{2}\\c)\,0\end{array}\)
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Đáp án : D(11) bình luận (0) lời giải
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) \(B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}}\)
\(\begin{array}{l}B = \frac{{{{2.6}^9} - {2^5}{{.18}^4}}}{{{2^2}{{.6}^8}}} = \frac{{{{2.6}^9} - {2^5}{{.6}^4}{{.3}^4}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^9} - {{2.2}^4}{{.3}^4}{{.6}^4}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^9} - {{2.6}^8}}}{{{2^2}{{.6}^8}}}\\ = \frac{{{{2.6}^8}\left( {6 - 1} \right)}}{{{2^2}{{.6}^8}}} = \frac{5}{2}\end{array}\)
\(\begin{array}{l}c)\,\,C = \left| {97\frac{2}{3} - 125\frac{3}{5}} \right| + 97\frac{2}{5} - 125\frac{1}{3}\\C = \left| {\frac{{293}}{3} - \frac{{628}}{5}} \right| + \frac{{487}}{5} - \frac{{376}}{3}\\C = \left| {\frac{{ - 419}}{{15}}} \right| + \frac{{487}}{5} - \frac{{376}}{3}\\C = \frac{{419}}{{15}} + \frac{{487}}{5} - \frac{{376}}{3}\\C = 0.\end{array}\)
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