Question

观察下列各式：1^3+2^3=1+8=9,而(1+2)^2=9……

Answer 1

(1)

1+2+3+4+5……+n

(n+1)*n*1/2

(2)

原式=(1^3+2^3+……+15^3)-(1^3+2^3+……+10^3)

=（1+2+……+15）^2-(1+……+10)^2

=120^2-55^2

=14400-3025

=11375