Thực hiện phép tính b) ( 1 + 2 /3 − 1/ 4 ) ( 0 , 8 − 3 /4 ) ^2 ;
Giải thích
b) \(\left( {1 + \frac{2}{3} - \frac{1}{4}} \right){\left( {0,8 - \frac{3}{4}} \right)^2}\)
\( = \left( {\frac{{12}}{{12}} + \frac{8}{{12}} - \frac{3}{{12}}} \right){\left( {\frac{4}{5} - \frac{3}{4}} \right)^2}\)
\( = \left( {\frac{{17}}{{12}}} \right){\left( {\frac{1}{{20}}} \right)^2}\)
\( = \frac{{17}}{{12}}\, \cdot \,\frac{1}{{400}} = \frac{{17}}{{4800}}\).