Advertisements (Quảng cáo)
Thực hiện các phép tính :
a) \({{ – 4} \over 5}.{{15} \over {16}}\) b) \({{ – 5} \over 6}.{{ – 3} \over {10}}\)
c) \({{ – 4} \over {27}}:{2 \over { – 9}}\) d) \({7 \over 6}:{{14} \over { – 9}}\)
e) \( – 18:{3 \over 5}\) f) \({3 \over 8}:\left( { – 9} \right)\).
Advertisements (Quảng cáo)
\(\eqalign{ & a){{ – 4} \over 5}.{{15} \over {16}} = {{( – 4).15} \over {5.16}} = {{( – 1).3} \over {1.4}} = {{ – 3} \over 4} \cr & b){{ – 5} \over 6}.{{ – 3} \over {10}} = {{( – 5).( – 3)} \over {6.10}} = {{( – 1).( – 1)} \over {2.2}} = {1 \over 4} \cr & c){{ – 4} \over {27}}:{2 \over { – 9}} = {{ – 4} \over {27}}.{{ – 9} \over 2} = {{( – 4).( – 9)} \over {27.2}} = {{( – 2).( – 1)} \over {1.3}} = {2 \over 3} \cr & d){7 \over 6}:{{14} \over { – 9}} = {7 \over 6}.{{ – 9} \over {14}} = {{7.( – 9)} \over {6.14}} = {{1.( – 3)} \over {2.2}} = {{ – 3} \over 4} \cr & e) – 18:{3 \over 5} = – 18.{5 \over 3} = {{( – 18).5} \over 3} = {{( – 6).5} \over 1} = – 30 \cr & f){3 \over 8}:( – 9) = {3 \over {8.( – 9)}} = {1 \over {8.( – 3)}} = {{ – 1} \over {24}} \cr} \)