|5x-3| < 2
<=> 5x-3 < 2 hay -(5x-3) < 2
<=> 5x-3 < 2 hay 5x-3 > -2
<=> 5x < 5 hay 5x >1
<=> x < 1 hay x > 0.2

b) |3x+1| >4 
Ta có : |3x+1|  ≥ 0 với mọi x 
mà |3x+1| > 4
=> |3x+1| ∈ { 5;6;7;8;....}
=> TH1: 3x+1 ∈ {5;6;7;8;.....} 
=> 3x ∈ { 4;5;6;7;....} 
=> x ∈ { 4/3;5/3;6/3;7/3;...}
=> x ≥ 4/3
=> TH2 : 3x+1 ∈ { -5;-6;-7;-8;...}
=> 3x ∈ { -6;-7;-8;-9 ;....}
=> x ∈ { -6/3;-7/3;-8/3;-9/3;....}
=> x  ≤ -6/3