Question

已知一组数据a1,a2,a3,a4,a5的平均数为1,且(a1)^2+(a2)^2+(a3)^2+(a4)^2+(a5)

Answer 1

=0.2(（a1-1)^2+...)=0.2((a1^2+...a5^2)-2(a1+...a5)+5)=0.2((a1^2+...a5^2)-5)