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Tính
a) \({{ – 3} \over 5}.{{15} \over { – 7}}.{{21} \over 6}\)
b) \({{ – 33} \over {25}}.{{15} \over {11}}.{{21} \over 6}\)
c) \({{ – 22} \over {25}}:{{11} \over 5}.{{21} \over 6}\)
d) \({{ – 3} \over 5}.\left[ {\left( { – {{15} \over {11}}} \right) – {{21} \over {33}}} \right]\)
Advertisements (Quảng cáo)
\(\eqalign{ & a){{ – 3} \over 5}.{{15} \over { – 7}}.{{21} \over 6} = – 3.{3 \over { – 7}}.{7 \over 2} = {9 \over 2} = 4{1 \over 2} \cr & b){{ – 33} \over {25}}.{{15} \over {11}}.{{21} \over {16}} = {{ – 3} \over 5}.{3 \over 1}.{{21} \over {16}} = {{ – 189} \over {80}} = – 2{{29} \over {80}} \cr & c){{ – 22} \over {25}}:{{11} \over 5}.{{21} \over {16}} = {{ – 22} \over {25}}.{5 \over {11}}.{{21} \over {16}} = {{ – 2} \over 5}.1.{{21} \over {16}} = {{ – 21} \over {40}} \cr & d){{ – 3} \over 5}.\left[ {\left( { – {{15} \over {11}}} \right) – {{21} \over {33}}} \right] = {{ – 3} \over 5}.\left( {{{ – 45 – 21} \over {33}}} \right) = {{ – 3} \over 5}.\left( { – {{66} \over {33}}} \right) = {6 \over 5} = 1{1 \over 5} \cr} \)