\(A=\dfrac{10^{11}-1}{10^{12}-1}\\ 10A=\dfrac{10^{12}-10}{10^{12}-1}\\ 10A=1-\dfrac{9}{10^{12}-1}\\ \)
\(B=\dfrac{10^{10}+1}{10^{11}+1}\\ 10B=\dfrac{10^{11}+10}{10^{11}+1}\\ 10B=1+\dfrac{9}{10^{11}+1}\)
Vì `10^(11)+1<10^(12)-1` nên \(\dfrac{9}{10^{11}+1}>\dfrac{9}{10^{12}-1}\\ \Rightarrow1+\dfrac{9}{10^{11}+1}>1-\dfrac{9}{10^{12}-1}\\ \Rightarrow10B>10A\\ \Rightarrow B>A\)