a(n+1) = 2a(n) - a(n-1),
a(n+2) = 2a(n+1)-a(n),
a(n+2) - a(n+1) = a(n+1) - a(n),
{a(n+1)-a(n)}是首项为a(2)-a(1)=3/4-1/4=1/2,的常数数列.
a(n+1) - a(n) = 1/2,
{a(n)}是首项为a(1)=1/4,公差为1/2的等差数列.
a(n) = 1/4 + (n-1)/2 = (2n-1)/4.
后面题目好像还没完哈~
a(n+1) = 2a(n) - a(n-1),
a(n+2) = 2a(n+1)-a(n),
a(n+2) - a(n+1) = a(n+1) - a(n),
{a(n+1)-a(n)}是首项为a(2)-a(1)=3/4-1/4=1/2,的常数数列.
a(n+1) - a(n) = 1/2,
{a(n)}是首项为a(1)=1/4,公差为1/2的等差数列.
a(n) = 1/4 + (n-1)/2 = (2n-1)/4.
后面题目好像还没完哈~