giúp em với 1/ 4( x – 5) – 7( 5 -x ) + 10 ( 5-x) = -3 2/ 3| x- 3| = 15 – |-9| + 7| -3| – (-24) 3/ 6 |x -3| – 9 | x-3| = -21

a, 4( x – 5) – 7( 5 -x ) + 10 ( 5-x) = -3

=> (-4). (5-x) – 7.(5-x) + 10.(5-x) = -3

=> (5-x) . (-4-7+10)= -3

=> (5-x). (-1) = -3

=> 5-x = 3

=> x = 2

Vậy x = 2

b, 3| x- 3| = 15 – |-9| + 7| -3| – (-24)

=> 3.|x-3| = 15 – 9 + 7.3 + 24

=> 3.|x-3| = 111

=> |x-3| = 37

=> \(\left[ \begin{array}{l}x-3=37\\x-3=-37\end{array} \right.\) 

=> \(\left[ \begin{array}{l}x=40\\x=-34\end{array} \right.\) 

Vậy x ∈ {-34;40}

c, 6 |x -3| – 9 | x-3| = -21

=> |x-3|. (6-9) = -21

=> |x-3| . (-3) = -21

=> |x-3| = 7

=> \(\left[ \begin{array}{l}x-3=7\\x-3=-7\end{array} \right.\) 

=> \(\left[ \begin{array}{l}x=10\\x=-4\end{array} \right.\) 

Vậy x ∈ {-4; 10}