Đề bài
Tính :
\[\eqalign{ & a]\left[ { - 3,2} \right].{{ - 15} \over {64}} + \left[ {0,8 - 2{4 \over {15}}} \right]:3{2 \over 3} \cr & b]\left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].\left[ {{1 \over 3} - 0,25 - {1 \over {12}}} \right]. \cr} \]
Lời giải chi tiết
\[\eqalign{ & a][ - 3,2].{{ - 15} \over {64}} + \left[ {0.8 - 2{4 \over {15}}} \right]:3{2 \over 3} = {{ - 32} \over {10}}.{{ - 15} \over {64}} + \left[ {{8 \over {10}} - {{34} \over {15}}} \right]:{{11} \over 3} = {3 \over 4} + \left[ {{4 \over 5} - {{34} \over 5}} \right]:{{11} \over 3} \cr & = {3 \over 4} + \left[ {{{12} \over {15}} - {{34} \over {15}}} \right]:{{11} \over 3} = {3 \over 4} + {{ - 22} \over {15}}.{3 \over {11}} = {3 \over 4} + {{ - 2} \over 5} = {{15} \over {20}} + {{ - 8} \over {20}} = {7 \over {20}} \cr & b]\left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].\left[ {{1 \over 3} = 0,25 - {1 \over {12}}} \right] = \left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].\left[ {{1 \over 3} - {1 \over 4} - {1 \over {12}}} \right] \cr & = \left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].\left[ {{4 \over {12}} - {3 \over {12}} - {1 \over {12}}} \right] = \left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].{0 \over {12}} \cr & = \left[ { - 6,17 + 3{5 \over 9} - 2{{36} \over {97}}} \right].0 = 0 \cr} \]