a) \(\displaystyle{\rm{}}{{5 + 10} \over {24}} = {15 \over {24}} = {5 \over 8}.\)
Vậy : \(\displaystyle{5 \over {24}} < {{5 + 10} \over {24}} = {5 \over 8}.\)
b) \(\displaystyle{{6 + 9} \over {6.9}} = {{15} \over {54}} = {5 \over {18}}\)
\(BCNN (9; 18; 3) = 18.\)
Quy đồng mẫu số các phân số ta có :
\(\displaystyle{4 \over 9} = {8 \over {18}}\;;\;\;\;{2 \over 3} = {{12} \over {18}}\;;\;\;\;{5 \over {18}} = {5 \over {18}}.\)
Ta có: \(\displaystyle{5 \over {18}} < {8 \over {18}} < {{12} \over {18}}\) hay \(\displaystyle{5 \over {18}} < {4 \over {9}} < {{2} \over {3}}.\)
Vậy: \(\displaystyle{{6 + 9} \over {6.9}} < {4 \over 9} < {2 \over 3}.\)
