???.........

bn ghi thiêú đề thì pải

\(\text{Ta thấy: }\sqrt{1+\frac{1}{1^2}+\frac{1}{2^2}}=1+\frac{1}{1}-\frac{1}{2}\)

\(\sqrt{1+\frac{1}{2^2}+\frac{1}{3^2}}=1+\frac{1}{2}-\frac{1}{3}\)

\(...................\)

\(\sqrt{1+\frac{1}{2009^2}+\frac{1}{2010^2}}\)

\(\text{Suy ra: }\sqrt{1+\frac{1}{1^2}+\frac{1}{2^2}}+\sqrt{1+\frac{1}{2^2}+\frac{1}{3^2}}+...+\sqrt{1+\frac{1}{2009^2}+\frac{1}{2010^2}}\)

\(=1+\frac{1}{1}-\frac{1}{2}+1+\frac{1}{2}-\frac{1}{3}+...+1+\frac{1}{2009}-\frac{1}{2010}\)

\(=2009+\frac{1}{1}-\frac{1}{2010}=2010-\frac{1}{2010}\)

tóc hơi cứng

thân,chân,tay gầy

chân ngắn

tham khảo nha bn