to get rid of the -3 from the modulus your going to bring it over the equal sign
|2x+1|=3
To get rid of the modulus you square both sides.
[tex] { (|2x+1|) }^{2} = {3}^{2} \\ {(2x + 1)}^{2} = {3}^{2} [/tex]
[tex](2x + 1 + 3) (2x + 1 - 3) = 0[/tex]
Postivite 3 solution is:
[tex]2x + 1 + 3 = 0 \\ 2x + 4 = 0 \\ 2x = - 4 \\ x - 2[/tex]
Negative 3 solution is
[tex]2x + 1 - 3 = 0 \\ 2x - 2 = 0 \\ 2x = 2 \\ x = 1[/tex]
Therefore x is -2 and 1