Bài 1; Tìm số nguyên x,biết a,13-|x| =|-4| b,|x|-3+6=16 c,35-|2x-1|=14 d|3x-2|+5=9-x

$a) 13 – | x | = | -4 |$

$⇒ 13 – | x | = 4$

$⇒ | x | = 13 – 4$

$⇒ | x | = 9$

$⇒\left[ \begin{array}{l}x=9\\x=-9\end{array} \right. $

$b) | x | – 3 + 6 = 16$

$⇒ | x | – 3 = 16 – 6 $

$⇒ | x | -3 = 10$

$⇒ | x | = 10 + 3$

$⇒ | x | = 13$

$⇒\left[ \begin{array}{l}x=13\\x=-13\end{array} \right.$

$c) 35 – | 2x – 1 | = 14$

$⇒ | 2x – 1 | = 35 – 14$

$⇒ | 2x – 1 | = 21$

$⇒\left[ \begin{array}{l}| 2x – 1 | = 21\\| 2x – 1 | = -21\end{array} \right.$

$⇒\left[ \begin{array}{l}x=20\\x=-11\end{array} \right.$

$d) | 3x – 2 | + 5 = 9 – x$

$⇒ | 3x – 2 | = 4 – x$

$⇒ 3x – 2 = 4 – x$ hoặc $3x – 2 = x – 4$

$⇒ 3x + x = 4 + 2$ hoặc $3x – x = -4 + 2$

$⇒ 4x = 6$ hoặc $2x = – 2$

$x = 1,5$ hoặc $1$

$⇒ x ∈ Z$ nên $x = -1$