Nội dung bài giảng
Rút gọn
a) \({{4.7} \over {9.32}}\) b) \({{3.21} \over {14.15}}\) c) \({{2.5.13} \over {26.35}}\)
d) \({{9.6-9.3} \over {18}}\) e) \({{17.5-17} \over {3-20}}\) f) \({{49+7.49} \over {49}}\)
Giải
a) \({{4.7} \over {9.32}} = {{4.7} \over {9.4.8}} = {7 \over {9.8}} = {7 \over {72}}\)
b) \({{3.21} \over {14.15}} = {{3.3.7} \over {2.7.3.5}} = {3 \over {2.5}} = {3 \over {10}}\)
c) \({{2.5.13} \over {26.35}} = {{2.5.13} \over {2.13.5.7}} = {1 \over 7}\)
d) \({\rm{}}{{9.6 - 9.3} \over {18}} = {{9.(6 - 3)} \over {9.2}} = {{6 - 3} \over 2} = {3 \over 2}\)
e) \({\rm{}}{{17.5 - 17} \over {3 - 20}} = {{17.(5 - 1)} \over { - 17}} = {{5 - 1} \over { - 1}} = - 4\)
f) \({{49 + 7.49} \over {49}} = {{49.(1 + 7)} \over {49}} = 1 + 7 = 8\)