Thực hiện phép tính :
a) \(4{1 \over 2}:\left( {2,5 - 3{3 \over 4}} \right) + {\left( {{{ - 1} \over 2}} \right)^2}\)
b) \(1{{13} \over {15}}.0,75 - \left( {{8 \over {15}} + 25\% } \right)\)
c) \(0,75 - {{43} \over {80}}:\left( {{{ - 4} \over 5} + 2,5.{3 \over 4}} \right)\)
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d) \(25\% - 1{1 \over 2} + 0,5.{{12} \over 5}\)
e) \(\left( { - 3,2} \right).{{ - 15} \over {64}} + \left( {0,8 - 2{4 \over {15}}} \right):3{1 \over 2}\).
\(\eqalign{ & a)4{1 \over 2}:\left( {2,5 - 3{3 \over 4}} \right) + {\left( {{{ - 1} \over 2}} \right)^2} = {9 \over 2}:\left( {{5 \over 2} - {{15} \over 4}} \right) + {1 \over 4} \cr & = {9 \over 2}:\left( {{{10} \over 4} - {{15} \over 4}} \right) + {1 \over 4} = {9 \over 2}:{{ - 5} \over 4} + {1 \over 4} = {9 \over 2}.{{ - 4} \over 5} + {1 \over 4} \cr & = {{ - 18} \over 5} + {1 \over 4} = {{ - 72} \over {20}} + {5 \over {20}} = {{ - 67} \over {20}} = - 3{7 \over {20}}. \cr & b)1{{13} \over {15}}.0,75 - \left( {{8 \over {15}} + 25\% } \right) = {{28} \over {15}}.{3 \over 4} - \left( {{8 \over {15}} + {1 \over 4}} \right) = {7 \over 5} - \left( {{{32} \over {60}} + {{15} \over {60}}} \right) \cr & = {7 \over 5} - {{47} \over {60}} = {{84} \over {60}} - {{47} \over {60}} = {{37} \over {60}}. \cr & c)0,75 - {{43} \over {80}}:\left( {{{ - 4} \over 5} + 2,5.{3 \over 4}} \right) = {3 \over 4} - {{43} \over {80}}:\left( {{{ - 4} \over 5} + {5 \over 2}.{3 \over 4}} \right) \cr & = {3 \over 4} - {{43} \over {80}}:\left( {{{ - 4} \over 5} + {{15} \over 8}} \right) = {3 \over 4} - {{43} \over {80}}:\left( {{{ - 32} \over {40}} + {{75} \over {40}}} \right) = {3 \over 4} - {{43} \over {80}}:{{43} \over {40}} \cr & = {3 \over 4} - {{43} \over {80}}.{{40} \over {43}} = {3 \over 4} - {1 \over 2} = {3 \over 4} - {2 \over 4} = {1 \over 4}. \cr & d)25\% - 1{1 \over 2} + 0,5{{12} \over 5} = {1 \over 4} - {3 \over 2} + {1 \over 2}.{{12} \over 5} \cr & = {1 \over 4} - {3 \over 2} + {6 \over 5} = {5 \over {20}} - {{30} \over {20}} + {{24} \over {20}} = {{ - 1} \over {20}} \cr & e)( - 3,2).{{ - 15} \over {64}} + \left( {0,8 - 2{4 \over {15}}} \right):3{1 \over 2} = - {{16} \over 5}.{{ - 15} \over {64}} + \left( {{4 \over 5} - {{34} \over {15}}} \right):{7 \over 2} \cr & = {3 \over 4} + \left( {{{12} \over {15}} - {{34} \over {15}}} \right):{7 \over 2} = {3 \over 4} + {{ - 22} \over {15}}.{2 \over 7} = {3 \over 4} + {{ - 44} \over {105}} = {{315} \over {420}} + {{ - 176} \over {420}} = {{139} \over {420}}. \cr} \)