Q:a1=2,a2=6,an+2−2an+1+an=2.求an.Q:a_{1}=2,a_{2}=6,a_{n+2}-2a_{n+1}+a_{n}=2.求a_{n}.Q:a1=2,a2=6,an+2−2an+1+an=2.求an.
A:an=n2+n.A:a_{n}=n^{2}+n.A:an=n2+n.
Q:a1=2,a2=6,an+2−2an+1+an=2.求an.Q:a_{1}=2,a_{2}=6,a_{n+2}-2a_{n+1}+a_{n}=2.求a_{n}.Q:a1=2,a2=6,an+2−2an+1+an=2.求an.
A:an=n2+n.A:a_{n}=n^{2}+n.A:an=n2+n.