初中数学七年级题库025:有理数加减乘除混合运算例题解析

初中数学七年级题库025:有理数加减乘除混合运算例题解析

例题:计算\(\displaystyle -{{3}^{2}}\div \left[ {{{{\left( {-\frac{1}{3}} \right)}}^{3}}\times {{{\left( {-3} \right)}}^{2}}+1\frac{3}{5}\div {{{\left( {-2} \right)}}^{2}}} \right]\)

答案:-135

解析:

原式\(\displaystyle =-9\div \left( {-\frac{1}{{27}}\times 9+\frac{8}{5}\div 4} \right)\)

\(\displaystyle =-9\div \left( {-\frac{1}{{27}}\times 9+\frac{8}{5}\times \frac{1}{4}} \right)\)

\(\displaystyle =-9\div \left( {-\frac{1}{3}+\frac{2}{5}} \right)\)

\(\displaystyle =-9\div \frac{1}{{15}}\)

\(\displaystyle =-9\times 15\)

\(\displaystyle =-135\)

注意:先乘方,再乘除,最后加减

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