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Rút gọn :
a) \(\dfrac{{5.3}}{{8.25}}\) b) \(\dfrac{{25.18}}{{9.40}}\)
c) \(\dfrac{{4.\left( { – 15} \right).2}}{{\left( { – 5} \right).24}}\) d) \(\dfrac{{19.5.20.14}}{{30.4.20.15}}\)
e) \(\dfrac{{7.19 – 7.11}}{{16.7}}\) f) \(\dfrac{{13.6 – 13}}{{4 – 17}}\)
g) \(\dfrac{{3024 – 12}}{{5192 – 21}}.\)
\(\eqalign{ & a){{5.3} \over {8.25}} = {{5.3} \over {8.5.5}} = {{1.3} \over {8.5.1}} = {3 \over {40}} \cr & b){{25.18} \over {9.40}} = {{5.5.9.2} \over {9.5.2.4}} = {{5.1.1.1} \over {1.1.1.4}} = {5 \over 4} \cr & c){{4.( – 15).2} \over {( – 5).24}} = {{4.( – 5).3.2} \over { – 5.4.3.2}} = 1 \cr & d){{19.5.20.14} \over {30.4.20.15}} = {{19.5.20.2.7} \over {30.2.2.20.5.3}} = {{19.1.1.1.7} \over {30.1.2.1.1.3}} = {{133} \over {180}} \cr & e){{7.19 – 7.11} \over {16.7}} = {{7.(19 – 11)} \over {16.7}} = {{7.8} \over {2.8.7}} = {{1.1} \over {2.1.1}} = {1 \over 2} \cr & f){{13.6 – 13} \over {4 – 17}} = {{13.(6 – 1)} \over { – 13}} = {{13.5} \over { – 13}} = – 5 \cr & g){{3024 – 12} \over {5292 – 21}} = {{12.252 – 12} \over {21.252 – 21}} = {{12.(252 – 1)} \over {2.(252 – 1)}} = {{12} \over {21}} = {4 \over 7} \cr} \)