It is an inequality, not an equation, what you have as solution is something like "
a greater than... /
a in... ".
First look at signs: what happens if
a<0?
Absolute values are always non negative: if

then
)
, if

then

. Solve these 2 cases separately (they are II degree equation), and do not forget the constrains on
a put when you split the absolute value in these 2 cases.