Đáp án:
\(\begin{array}{l}
a,\,\,\,\,\, - 7990\\
b,\,\,\,\,\,63
\end{array}\)
Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
\left( { - {{2.10}^5} - {{6.10}^5} + {{10}^3}} \right):100\\
= \left( { - {{8.10}^5} + {{10}^3}} \right):100\\
= \left[ {{{10}^3}.\left( { - {{8.10}^2} + 1} \right)} \right]:100\\
= \left[ {1000.\left( { - 800 + 1} \right)} \right]:100\\
= \left[ {1000.\left( { - 799} \right)} \right]:100\\
= 10.\left( { - 799} \right)\\
= - 7990\\
b,\\
\left( {{{2.27}^2} + {3^8} - {{4.9}^3}} \right):{9^2}\\
= \left[ {2.{{\left( {{3^3}} \right)}^2} + {{\left( {{3^2}} \right)}^4} - {{4.9}^3}} \right]:{9^2}\\
= \left[ {{{2.3}^6} + {9^4} - {{4.9}^3}} \right]:{9^2}\\
= \left[ {2.{{\left( {{3^2}} \right)}^3} + {9^4} - {{4.9}^3}} \right]:{9^2}\\
= \left( {{{2.9}^3} + {9^4} - {{4.9}^3}} \right):{9^2}\\
= \left( {{9^4} - {{2.9}^3}} \right):{9^2}\\
= \left[ {{9^3}.\left( {9 - 2} \right)} \right]:{9^2}\\
= \left( {{{7.9}^3}} \right):{9^2}\\
= {7.9^3}:{9^2}\\
= 7.9\\
= 63
\end{array}\)
