Đáp án đúng: A
Giải chi tiết:\(\eqalign{& a)\,\,195 - 3(x - 5) = 12 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,3(x - 5)\, = 195 - 12 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,3(x - 5) = 183 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x - 5 = 183:3 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x - 5 = 61 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\, = 61 + 5 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\, = 66. \cr} \) \(\eqalign{ & b)\,\,{(x - 4)^8}:{3^2} = {9^3} \cr & \,\,\,\,\,\,{(x - 4)^8}\,\,\,\,\,\,\,\,\,\,\, = {({3^2})^3}{.3^2} \cr & \,\,\,\,\,\,{(x - 4)^8}\,\,\,\,\,\,\,\,\,\,\, = {3^6}{.3^2} \cr & \,\,\,\,\,\,{(x - 4)^8}\,\,\,\,\,\,\,\,\,\,\, = {3^8} \cr & \,\,\,\,\,\,\,x - 4\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3 \cr & \,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3 + 4 \cr & \,\,\,\,\,\,\,x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 7. \cr} \)
