Nội dung bài giảng
Tính:
\(a{)25^3}:{5^2};\)
\(b){\left( {{3 \over 7}} \right)^{21}}:{\left( {{9 \over {49}}} \right)^6};\)
\(c)3 - {\left( { - {6 \over 7}} \right)^0} + {\left( {{1 \over 2}} \right)^2}:2\)
Giải
\(a{)25^3}:{5^2} = {25^3}:25 = {25^2} = 625\)
\(b){\left( {{3 \over 7}} \right)^{21}}:{\left( {{9 \over {49}}} \right)^6} = {\left( {{3 \over 7}} \right)^{21}}:{\left[ {{{\left( {{3 \over 7}} \right)}^2}} \right]^6} \)
\(= {\left( {{3 \over 7}} \right)^{21}}:{\left( {{3 \over 7}} \right)^{12}} = {\left( {{3 \over 7}} \right)^9} = {{19683} \over {40353607}}\)
\(c) 3 - {\left( { - {6 \over 7}} \right)^0} + {\left( {{1 \over 2}} \right)^2}:2 = 3 - 1 + {\left( {{1 \over 2}} \right)^2}\)
\(= 2 + {1 \over 8} = 2{1 \over 8}\)