Tìm \(\frac{{13}}{4}\) của \(1\frac{{13}}{{15}}.0,75 - \left( {\frac{{56}}{{105}} + 25\% } \right).\frac{{24}}{{47}} - 3\frac{{12}}{{13}}:3\)
Bước 1: Tính \(1\frac{{13}}{{15}}.0,75 - \left( {\frac{{56}}{{105}} + 25\% } \right).\frac{{24}}{{47}} - 3\frac{{12}}{{13}}:3\)
Bước 2: Tìm \(\frac{a}{b}\) của c bằng \(\frac{a}{b}\) . c
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Ta có:
\(\begin{array}{l}1\frac{{13}}{{15}}.0,75 - \left( {\frac{{56}}{{105}} + 25\% } \right).\frac{{24}}{{47}} - 3\frac{{12}}{{13}}:3\\ = \frac{{28}}{{15}}.\frac{3}{4} - \left( {\frac{8}{{15}} + \frac{1}{4}} \right).\frac{{24}}{{47}} - \frac{{51}}{{13}}.\frac{1}{3}\\ = \frac{7}{5} - \left( {\frac{{32}}{{60}} + \frac{{15}}{{60}}} \right).\frac{{24}}{{47}} - \frac{{17}}{{13}}\\ = \frac{7}{5} - \frac{{47}}{{60}}.\frac{{24}}{{47}} - \frac{{17}}{{13}}\\ = \frac{7}{5} - \frac{2}{5} - \frac{{17}}{{13}}\\ = 1 - \frac{{17}}{{13}}\\ = \frac{{13}}{{13}} - \frac{{17}}{{13}}\\ = \frac{{ - 4}}{{13}}\end{array}\)
Như vậy, \(\frac{{13}}{4}\) của \(1\frac{{13}}{{15}}.0,75 - \left( {\frac{{56}}{{105}} + 25\% } \right).\frac{{24}}{{47}} - 3\frac{{12}}{{13}}:3\) là:
\(\frac{{13}}{4}.\frac{{ - 4}}{{13}} = - 1\)