\(a=\left(\frac{1}{2}+1\right)\left(\frac{1}{3}+1\right)\left(\frac{1}{4}+1\right)...\left(\frac{1}{99}+1\right)\)
\(a=\frac{3}{2}.\frac{4}{3}.\frac{5}{4}....\frac{100}{99}\)
\(\Rightarrow a=\frac{100}{2}\)
\(\Rightarrow a=50\)
Xét \(a^2-1\)
Thay a=50 ta có :
\(50^2-1\)
\(=2500-1\)
\(=2499\)
Ta có :\(B=49.50\)
\(\Rightarrow B=2450\)
Mà \(2450< 2499\)
\(\Rightarrow a>B\)