减函数f(x)定义在闭区间-1,1上且是奇函数,若f(a*a-a-1)+f(4a-5)>0 求a
问题描述:
减函数f(x)定义在闭区间-1,1上且是奇函数,若f(a*a-a-1)+f(4a-5)>0 求a
若f(a*a-a-1)+f(4a-5)>0 求a的范围
答
f(x)定义在闭区间-1,1上→-1≤a*a-a-1≤1-1≤4a-5≤1→1≤a≤1.5 ①f(x)是奇函数→-f(4a-5)=f(-(4a-5))=f(5-4a)f(a*a-a-1)+f(4a-5)>0→f(a*a-a-1)>-f(4a-5)=f(5-4a)又f(x)是减函数→a*a-a-1<5-4a→(-3-√33)/2<a...