a ) $x + 9 = 2 - 17$
$ x + 9 = - 15$
$ x = - 15 - 9 = - 24$
Vậy $x = - 24$
b) $x - 17 = ( - 11 ) . ( - 5 )$
$x - 17 = 55$
$x = 55 + 17$
$ x = 72$
Vậy$ x = 72$
c) $| x - 5 | = ( - 4 )²$
$| x - 5 | = 16$
⇒\(\left[ \begin{array}{l}x - 5 = 16⇔ x = 16 +5=21\\x-5=-16⇔ x=-16+5=-11\end{array} \right.\)
d ) $2x + 5 = x - 1 $
$x = - 1 - 5 $
$x = -6$
Vậy $x = - 6$