Easy
S = 22 + 42 + 62 + ... + 202
S = 22 ( 12 + 22 + 32 + ... + 102 )
Vì 12 + 22 + 32 + ... + 102 = 385
=> S = 22 . 385
S = 4 . 385
S = 1540
Vậy ...
Hok tốt :))
\(S=2^2+4^2+6^2+...+20^2\)
Theo đề ra ta có: \(1^2+2^2+3^2+...+10^2=385\)
\(\Rightarrow S=2\left(1^2+2^2+3^2+...+10^2\right)\)
\(\Rightarrow S=2\cdot385\)
\(\Rightarrow S=770\)