a)\(A=\frac{4^6.9^5+6^9.120}{-8^4.3^{12}-6^{11}}=\frac{\left(2^2\right)^6+\left(3^2\right)^5+2^9.3^9.2^3.3.5}{-\left(2^3\right)^4.3^{13}-2^{11}.3^{11}}\)
\(=\frac{2^{12}.3^{10}+2^{12}.3^{10}.5}{-2^{12}.3^{12}-2^{11}.3^{11}}=\frac{2^{12}.3^{10}.\left(1+5\right)}{-2^{11}.3^{11}.\left(2.3+1\right)}=\frac{2.6}{-3.7}=-\frac{4}{7}\)
b)\(B=\frac{1}{1-\frac{1}{1-2}}+\frac{1}{1+\frac{1}{1+2^{-1}}}=\frac{1}{1-\frac{1}{-1}}+\frac{1}{1+\frac{1}{1+\frac{1}{2}}}\)
\(=\frac{1}{1+1}+\frac{1}{1+\frac{1}{\frac{3}{2}}}=\frac{1}{2}+\frac{1}{1+\frac{2}{3}}+\frac{1}{2}+\frac{1}{\frac{5}{3}}=\frac{1}{2}+\frac{3}{5}=\frac{11}{10}\)
Ban tải photmack về mà dùng hiệu quả lắm dó