Question

cho 1²+2²+3²+..........+10²=385

Tính A=100²+200²+300²+.......+1000²

Answer 1

A=(1.100)^2+(2.100)^2+(3.100)^2+...+(10.100)^2

=1^2.100^2+2^2.100^2+3^2.100^2+....+10^2.100^2

=100^2.(1^2+2^2+3^2+...+10^2)

=10000.385=3850000