rút gọn phân số
\(\frac{1.3.5...97.99}{51.52.53...99.100}\)
tính A:B
A=\(\frac{100^2+1^2}{100.1}\)+\(\frac{99^2+2^2}{99.2}\)+\(\frac{98^2+3^2}{98.3}\)+...+\(\frac{51^2+50^2}{51.50}\)
B=\(\frac{1}{2}\)+\(\frac{1}{3}\)+\(\frac{1}{4}\)+...+\(\frac{1}{100}\)