Đề bài
1. >; ; 2{6 \over 7}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,3{2 \over 7}\, < \,3{5 \over 7} \cr
& 8{6 \over {10}}\, = \,8{3 \over 5}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,9{1 \over 2}\, > \,5{1 \over 2} \cr} \]
2. Chuyển các hỗn số sau thành phân số rồi thực hiện phép tính
a]
\[2{1 \over 8} + 1{3 \over 4} = {{17} \over 8} + {7 \over 4} = {{17} \over 8} + {{14} \over 8} = {{17 + 14} \over 8} = {{31} \over 8}\]
\[3{2 \over 7} + 1{3 \over 7} = {{23} \over 7} + {{10} \over 7} = {{23 + 10} \over 7} = {{33} \over 7}\]
b]
\[5{1 \over 3} - 2{5 \over 6} = {{16} \over 3} - {{17} \over 6} = {{32} \over 6} - {{17} \over 6} = {{32 - 17} \over 6} = {{15} \over 6} = {5 \over 2}\]
\[4{7 \over 9} - 1{5 \over 9} = {{43} \over 9} - {{14} \over 9} = {{43 - 14} \over 9} = {{29} \over 9}\]
c]
\[2{4 \over 5} \times 3{1 \over 8} = {{14} \over 5} \times {{25} \over 8} = {{14 \times 25} \over {5 \times 8}} = {{350} \over {40}} = {{35} \over 4}\]
\[1{1 \over 5}:1{4 \over 5} = {6 \over 5}:{9 \over 5} = {6 \over 5} \times {5 \over 9} = {2 \over 3}\]
3. Tính
\[{{9 \times 42} \over {14 \times 27}} = {{9 \times 3 \times 14} \over {14 \times 3 \times 9}} = 1\]