f(x)∈(-4a^2+2a+6,+∞)-4a^2+2a+6≥02a^2-a-3≤0(2a-3)(a+1)≤0-1≤a≤3/2f(a)=2-a|a+3| a∈[-1,3/2]a|a+3|∈[-2,27/4]2-a|a+3|∈[-19/4,4]数学辅导团团员为您解答,有错误请指正,不明白请追问.没问题就采纳吧,真心...