Bài 176: trang 67 sgk Toán 6 tập 2
Tính:
a) \(1{{13} \over {15}}.{\left( {0,5} \right)^2}.3 + \left( {{8 \over {15}} - 1{{19} \over {60}}} \right) \div 1{{23} \over {24}}\)
b) \({{\left( {{{{{11}^2}} \over {200}} + 0,415} \right) \div 0,01} \over {{1 \over {12}} - 37,25 + 3{1 \over 6}}}\)
Bài Làm:
a) \(1{{13} \over {15}}.{\left( {0,5} \right)^2}.3 + \left( {{8 \over {15}} - 1{{19} \over {60}}} \right) \div 1{{23} \over {24}}\)
\( = {{28} \over {15}}.{\left( {{1 \over 2}} \right)^2}.3 + \left( {{{32} \over {60}} - {{79} \over {60}}} \right) \div {{47} \over {24}}\)
\( = {{28} \over {15}}.{1 \over 4}.3 + \frac{-47}{60} . {{24} \over {47}}\)
\( = {7 \over 5} + {{ - 2} \over 5}\)
\( = {5 \over 5} = 1\)
b) \({{\left( {{{{{11}^2}} \over {200}} + 0,415} \right) \div 0,01} \over {{1 \over {12}} - 37,25 + 3{1 \over 6}}}\)
\( = {{\left( {{{121} \over {200}} + {{415} \over {1000}}} \right).100} \over {{1 \over {12}} - {{149} \over 4} + {{19} \over 6}}}\)
\( = {{\left( {{{121} \over {200}} + {{83} \over {200}}} \right).100} \over {{{1 - 447 + 38} \over {12}}}}\)
\( = \left( {{{204} \over {200}}.100} \right) \div (-34)\)
\( = {{102} \over {100}}.100.{{ - 1} \over {34}}\)
\( = {{ 102} \over{-34}} = - 3\)
