Question

How do you solve `3 > abs(a + 1)`?

Answer 1

`abs(a+1)` is either equal to `a+1` ( if `a+1>0` )
or `-a-1` ( if `a+1<0` )

Thus :

• `3>a+1`
  `3-1>a` ( we substract 1 on each side )
  `2>a`
  `a<2`

Or :

• `3> -a-1`
  `3+1> -a` ( we add 1 on each side )
  `4> -a`
  `-4< a` ( we multiply by `-1` on each side, and thus `>` becomes `<` )
  `a> -4`