(2)设 a(n+1)=pan+q
令bn=an +a(n+1)
则 bn=an+pan +q=(p+1)·an +q
b(n+1)=(p+1)·a(n+1) +q
=(p+1)·(pan+q) +q
=(p+1)p·an +pq +2q
=p[(p+1)·an +q] +2q
=p·bn+2q
从而 {bn}也是“M类数列”,
即数列{an+an+1}也是“M类数列”
(2)设 a(n+1)=pan+q
令bn=an +a(n+1)
则 bn=an+pan +q=(p+1)·an +q
b(n+1)=(p+1)·a(n+1) +q
=(p+1)·(pan+q) +q
=(p+1)p·an +pq +2q
=p[(p+1)·an +q] +2q
=p·bn+2q
从而 {bn}也是“M类数列”,
即数列{an+an+1}也是“M类数列”