`a)13-|x|=|-4|`
`⇔13-|x|=4`
`⇔|x|=13-4`
`⇔|x|=9`
`⇔x=± 9.`
` text{Vậy x=±9.}`
`b)|x-15|+6=16`
`⇔|x-15|=16-6`
`⇔|x-15|=10`
`⇔` \(\left[ \begin{array}{l}x-15=10\\x-15=-10\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=25\\x=5\end{array} \right.\) .
` Vậy ` `x∈{25;5}.`
`c)35-|2x-1|=14`
`⇔|2x-1|=35-14`
`⇔|2x-1|=21`
`⇔` \(\left[ \begin{array}{l}2x-1=21\\2x-1=-21\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x=22\\2x=-20\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=10\\x=-11\end{array} \right.\) .
` Vậy ` `x∈{-11;10}.`
`d)2.|25-x|-|45|=-23`
`⇔2.|25-x|-45=-23`
`⇔2.|25-x|=-23+45`
`⇔2.|25-x|=22`
`⇔|25-x|=11`
`⇔` \(\left[ \begin{array}{l}25-x=11\\25-x=-11\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=14\\x=36\end{array} \right.\) .
` Vậy ` `x ∈{14;36}.`
