由题意,得
a(n+1)-an>0
[2(n+1)²-b(n+1)+12]-(2n²-bn+12)
=4n+2-b
b为常数,2-b为常数,随n增加,4n+2-b单调递增,要对任意n∈N+,4n+2-b>0均成立,则4n+2-b取最小值时,即当n=1时,不等式成立.
4+2-b>0
由题意,得
a(n+1)-an>0
[2(n+1)²-b(n+1)+12]-(2n²-bn+12)
=4n+2-b
b为常数,2-b为常数,随n增加,4n+2-b单调递增,要对任意n∈N+,4n+2-b>0均成立,则4n+2-b取最小值时,即当n=1时,不等式成立.
4+2-b>0