Đáp án:

\(\begin{array}{l}
a)A = \dfrac{2}{3}\\
b)B = \dfrac{{72}}{5}
\end{array}\)

Giải thích các bước giải:

\(\begin{array}{l}
a)A = \dfrac{{{{2.2}^{3.4}}{{.3}^{3.2}} + {2^2}{{.2}^9}{{.3}^9}}}{{{2^7}{{.2}^7}{{.3}^7} + {2^7}{{.2}^3}{{.5.3}^{2.4}}}}\\
 = \dfrac{{{2^{13}}{{.3}^6} + {2^{11}}{{.3}^9}}}{{{2^{14}}{{.3}^7} + {2^{10}}{{.3}^8}.5}}\\
 = \dfrac{{{2^{11}}{{.3}^6}\left( {{2^2} + {3^3}} \right)}}{{{2^{10}}{{.3}^7}.\left( {{2^4} + 3.5} \right)}}\\
 = \dfrac{{2.31}}{{3.31}} = \dfrac{2}{3}\\
b)B = \left( {\dfrac{{{2^3}}}{{{3^3}}}.\dfrac{{{3^2}}}{{{4^2}}}.\left( { - 1} \right)} \right):\left( {\dfrac{{{2^2}}}{{{5^2}}}.\left( { - \dfrac{{{5^3}}}{{{{12}^3}}}} \right)} \right)\\
 = \left( {\dfrac{{{2^3}}}{{{3^3}}}.\dfrac{{{3^2}}}{{{2^{2.2}}}}.\left( { - 1} \right)} \right):\left( {\dfrac{{{2^2}}}{{{5^2}}}.\left( { - \dfrac{{{5^3}}}{{{2^{2.3}}{{.3}^3}}}} \right)} \right)\\
 = \dfrac{{ - 1}}{{2.3}}:\dfrac{{ - 5}}{{{2^3}{{.3}^3}}}\\
 = \dfrac{1}{{2.3}}.\dfrac{{{2^4}{{.3}^3}}}{5}\\
 = \dfrac{{{2^3}{{.3}^2}}}{5} = \dfrac{{72}}{5}
\end{array}\)

@Namelesszz206

Nhớ vote mình 5 sao, cảm ơn và ctlhn.

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