|2x²-5x-1|＜3
-3＜2x²-5x-1＜3
-3＜2x²-5x-1
2x²-5x+2>0
(2x+1)(x+2)>0
x-1/2
2x²-5x-1＜3
2x²-5x＜4
x²-5x/2＜2
x²-5x/2+(5/4)²＜2+25/16
(x-5/4)²＜57/16
x-5/4>√57 /4或x-5/4(5+√57)/4 或x(5+√57)/4 或x