求解下列各一元二次不等式:
(1) 4x2-1≥0 (2) x-x2+6<0 (3) x2+x-6<0
(1) 4x2-1≥0
x2≥1/4
x≥1/2或x≤-1/2
(2) x-x2+6<0
x2-x-6>0
(x-3)(x+2)>0
x>3或x<-2
(3) x2+x-6<0
(x+3)(x-2)<0
-3<x<2