Nội dung bài giảng
Tính:
a) \({4 \over 7}:\left( {{2 \over 5}.{4 \over 7}} \right)\)
b) \({6 \over 7} + {5 \over 7}:5 - {8 \over 9}\)
Giải
\(a){4 \over 7}:\left( {{2 \over 5}.{4 \over 7}} \right) = {4 \over 7}:{8 \over {35}} = {4 \over 7}.{{35} \over 8} = {5 \over 2}\)
\(b){6 \over 5} + {5 \over 7}:5 - {8 \over 9} = {6 \over 5} + {5 \over 7}.{1 \over 5} - {8 \over 9} = {6 \over 7} + {1 \over 7} - {8 \over 9} = 1 - {8 \over 9} = {1 \over 9}\)