Question

Cho biết

\(1^{2+2^2+3^2+.......+10^2=385}\)

Tính tổng:

a)\(^{2^2+4^2+6^2+........+20^2}\)

b)\(\left(0,25\right)^2+\left(0,5\right)^2+...........+\left(2,5\right)^2\)

Answer 1

\(a,2^2+4^2+6^2+...+20^2\)

\(=1^2.2^2+2^2.2^2+3^2.2^2+...+10^2.2^2\)

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

\(=385.4\)

\(=1540\)

\(b,\left(0.25\right)^2+\left(0.5\right)^2+...+\left(2.5\right)^2\)

\(=1^2.0,25^2+2^2.0,25^2+...+10^2.0,25^2\)

\(=\left(1^2+2^2+...+10^2\right).0,25^2\)

\(=385.0.0625\)

\(=24.0625\)

Answer 2

a/ Có tự ghi lại đề

= ((2+8)+(4+6)+10+(12+18)+(14+16)+20))^2

= ((10+10+10+30+30+20))^2

=(110)^2

=100^2+10^2

=10000+100

=10100