nguyên âm hay nguyên dương hạ

\(A=1+\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}\)

ta có :

\(\frac{1}{2^2}<\frac{1}{1.2}\)

\(\frac{1}{3^2}<\frac{1}{2.3}\)

...

\(\frac{1}{50^2}<\frac{1}{49.50}\)

-->\(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}<\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{49.50}\)

-> \(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}<\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{49}-\frac{1}{50}\)

-->\(\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{50^2}<\frac{49}{50}<1\)

\(A=\frac{2015+2016}{2016+2017}=\frac{2015}{2016+2017}+\frac{2016}{2016+2017}\)

\(B=\frac{2015}{2016}+\frac{2016}{2017}\)

vì \(\frac{2015}{2016+2017}<\frac{2015}{2016}\)và \(\frac{2016}{2016+2017}<\frac{2016}{2017}\)

nên A <B

có nhưng bạn hãy kết bạn đi

dấu bằng khi a=b=c=2 là đúng

có 4 góc nhà