Đáp án đúng: A
Giải chi tiết:\(\eqalign{& {\left( {12x - 4} \right)^3}{.8^3} = {4^6}{.16^3} \cr & {\left( {12x - 4} \right)^3}.{\left( {{2^3}} \right)^3} = {\left( {{2^2}} \right)^6}.{\left( {{2^4}} \right)^3} \cr & {\left( {12x - 4} \right)^3}{.2^9}\,\,\,\,\,\,\,\,\, = {2^{12}}{.2^{12}} \cr & {\left( {12x - 4} \right)^3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {2^{24}}:{2^9} \cr & {\left( {12x - 4} \right)^3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {2^{15}} \cr & {\left( {12x - 4} \right)^3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {({2^5})^3} \cr & 12x - 4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {2^5} = 32 \cr} \)
\(\eqalign{& 12x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 32 + 4 \cr & \,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 36:12 \cr & \,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3. \cr} \)
