\(a,\frac{7\cdot9-14}{3-17}\) \(b,0,25.2\frac{1}{3}.30.0,5.\frac{8}{45}\)
\(c,\frac{9}{23}.\frac{5}{8}+\frac{9}{23}.\frac{3}{8}-\frac{9}{23}\) \(d,(4\frac{1}{9}+3\frac{1}{4}).2\frac{1}{4}+2\frac{3}{4}\)
\(e,(-0,75+\frac{1}{2}):\frac{4}{3}\) \(f,\frac{5}{9}.\frac{2}{7}+\frac{5}{9}.\frac{5}{7}-\frac{8}{3}\)
\(g,7,5.1\frac{3}{4}-6\frac{2}{5}\) \(h,1\frac{13}{15}.0,75-(\frac{8}{15}+25\%)\)
Mình làm câu a,c, thôi , còn bạn làm nốt bài b,d, nhé
\(a,\frac{7\cdot9-14}{3-17}=\frac{63-14}{3-17}=\frac{49}{-14}=\frac{7\cdot7}{(-2)\cdot7}=\frac{7}{-2}=\frac{-7}{2}\)
\(c,\frac{9}{23}\cdot\frac{5}{8}+\frac{9}{23}\cdot\frac{3}{8}-\frac{9}{23}\)
\(=\frac{9}{23}\cdot\left[\frac{5}{8}+\frac{3}{8}-1\right]\)
\(=\frac{9}{23}\cdot\left[1-1\right]=\frac{9}{23}\cdot0=0\)
Bổ sung hai ý còn lại :
b) \(0,25\cdot2\frac{1}{3}\cdot30\cdot0,5\cdot\frac{8}{45}\)
\(=\frac{1}{4}\cdot\frac{7}{3}\cdot30\cdot\frac{1}{2}\cdot\frac{8}{45}\)
\(=\frac{1\cdot7\cdot30\cdot1\cdot8}{4\cdot3\cdot1\cdot2\cdot45}\)
\(=\frac{7\cdot30\cdot8}{8\cdot3\cdot45}\)
\(=\frac{210}{135}=\frac{14}{9}\)
d) \(\left(4\frac{1}{9}+3\frac{1}{4}\right)\cdot2\frac{1}{4}+2\frac{3}{4}\)
\(=\left(\frac{37}{9}+\frac{13}{4}\right)\cdot\frac{9}{4}+\frac{11}{4}\)
\(=\frac{265}{36}\cdot\frac{9}{4}+\frac{11}{4}\)
\(=\frac{265}{16}+\frac{11}{4}\)
\(=\frac{309}{16}\)
