1, unary quadratic inequality: (a0, x 1, X2 is two roots corresponding to unary quadratic equation) Discriminant △_0△=0△_0 unary quadratic inequality ax2bxc0{x|xx 1 or xx2} {x | XB} R. 0cxdcxd0 ⑶ AXB0 (AXB) (CXD) 0cxd ⑶ AXB0 (AXB) (CXD) 0cxd0cxd _ 3. Absolute inequality: (c & gt0) (1) | AXB | CCA XBC vocational high school mathematics common formula (2)_ x000e _ | AX _ x005f _ x005f _ x000e _ b | _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x005f _ x0000e _ c _ x005f _ x005f _ x005f _ x0005f _ x0005f _ x0005 f