观察下列各式:1x2x3x4+1=25=5^2,2x3x4x5+1=121=11^2,3x4x5x6+1=361=19^2,……
观察下列各式:1x2x3x4+1=25=5^2,2x3x4x5+1=121=11^2,3x4x5x6+1=361=19^2,……
日期:2008-04-03 20:59:20 人气:1
n(n+1)(n+2)(n+3)+1=(n^2+3n+1)^2
n(n+1)(n+2)(n+3)+1
=[n(n+3)][(n+1)(n+2)]+1
=(n^2+3n)(n^2+3n+2)+1
=(n^2+3n)^2+2(n^2+3n)+1
=(n^2+3n+1)^2