Question

Biết: \(1^2+2^2+3^2+....+10^2=385\)

Tính: S = \(2^2+4^2+6^2+....+20^2\)

GIÚP MIK VỚI MAI MIK NỘP RÙI HEPL ME

Answer 1

Ta có: \(S=\left(1.2\right)^2+\left(2.2\right)^2+\left(3.2\right)^2+...+\left(10.2\right)^2\)

\(\Rightarrow S=1.2^2+2^2.2^2+3^2.2^2+..+10^2.2^2\)

\(\Rightarrow S=2^2\left(1+2^2+3^2+..+10^2\right)\)

\(\Rightarrow S=4.385=1540\)

Answer 2

ta có : S=\(\left(2.1\right)^2+\left(2.2\right)^2+\left(2.3\right)^2+..+\left(2.10\right)^2\)

=\(2^2\left(1^2+2^2+3^2+...+10^2\right)\)

=4.385 =1540

Answer 3

\(S=4.358=...\)

Answer 4

S=1540