2a^2+a+1=2(a+1/4)^2+7/8>0 2a^2-2a+3=2(a-1/2)^2+5/2>0
函数f(x)在R上是偶函数,在区间(-∞,0)上递增,则在(0,+∞)上递减,f(2a^2+a+1)<f(2a^2-2a+3)
所以2a^2+a+1 >2a^2-2a+3 a>2/3
2a^2+a+1=2(a+1/4)^2+7/8>0 2a^2-2a+3=2(a-1/2)^2+5/2>0
函数f(x)在R上是偶函数,在区间(-∞,0)上递增,则在(0,+∞)上递减,f(2a^2+a+1)<f(2a^2-2a+3)
所以2a^2+a+1 >2a^2-2a+3 a>2/3