Given $ -3 - x \lt x - 4 \lt -3 + x $, I want to add absolute value bracket to $x - 4$, making it $ |x - 4| \lt a $.
$\because|x - 4| < a$ means $ -a \lt x - 4 \lt a . $
$ \because-(- 3- x) > (-3 + x) $
$ \therefore -3 -x \lt x - 4\lt -3 + x \lt 3+ x$
$ \therefore |x - 4| < 3+ x $
Is this correct?
We have
$$-3 - x \lt x - 4 \iff x> \frac12$$
$$x - 4 \lt -3 + x \iff -4<-3$$
therefore
$$|x - 4| \ge 0 $$