Question

若函數(shù)f(x)=lg(x²+ax-a-1)在區(qū)間［2,+∞)上單調(diào)遞增,則實(shí)數(shù)a的取值范圍是       .

Answer 1

(-3,+∞)

解析:∵函數(shù)f(x)在區(qū)間［2,+∞）上單調(diào)遞增,

∴-≤2,且x=2時(shí),x²+ax-a-1＞0,即

∴

∴a＞-3,即實(shí)數(shù)a的取值范圍是(-3,+∞).