因为f(x)是偶函数,所以f(-x)=f(x),所以f(-3/4)=f(3/4)又由a*a-a+1=a^2-a+1/4+3/4=(a-1/2)^2+3/4,因为(a-1/2)^2>=0所以a*a-a+1>=3/4又因为f(x)在[0,+oo)上为减函数,所以f(3/4)>=f(a*a-a+1)所以f(-3/4)>=f(a*a-a+1)...