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已知非零向量 满足： (α，β，γ∈R)，B、C、D为不共线的三个点，给出下列命题： ①若 ，γ=-1，则A、B、C、D四点共面； ②当α＞0，β＞0，γ= 时，若 ， ， ，则α+β的最大值是 ； ③已知正项等差数列{a n }(n∈N*)，若α=a 2 ，β=a 2009 ，γ=0，且A、B、C三点共线，但O点不在直线BC上，则的最小值为9； ④若α+β=1(αβ≠0)，γ=0，则A、B、C三点共线且点A分 所成的比A一定为 ； 其中你认为正确的所有命题的序号是（ ）。
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