Bạn tham khảo nhé
A=14 +116 +136 +164 +1100 +1144 +1196 =122 +142 +162 +182 +1102 +1122 +1142
2A=222 +242 +262 +282 +2102 +2122 +2142
2A<12 +22.4 +24.6 +26.8 +28.10 +210.12 +212.14
2A<12 +12 −14 +14 −1
Đặt \(A\)\(=\frac{1}{2^2}+\frac{1}{4^2}+...+\frac{1}{100^2}\)
Ta có: \(A< \frac{1}{2^2-1}+\frac{1}{4^2-1}+...+\frac{1}{100^2-1}\)
\(A< \frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{99.101}\)
\(A< \frac{1}{2}.\left(1-\frac{1}{101}\right)\)
\(A< \frac{1}{2}.1\)( VÌ \(1-\frac{1}{101}< 1\))
\(A< \frac{1}{2}\)
BFF bạn thân tri kỷ viết sai đề bài rùi
