Réponse :
Bonjour,
Exercice 5:
A) 5x - 1 = 3x + 9 -> 5x - 3x = 9 + 1 -> 2x = 10 -> x = 5
B) x + 8 = 2x - 7 -> x - 2x = -7 - 8 -> -x = - 15 -> x=15
C) 25 + 5x = 7 - 3x -> 5x + 3x = 7 - 25 -> 8x = - 18 -> x= -2,25
D) [tex]\frac{x}{5}[/tex] - 8 = 10 -> x= 90
E) [tex]10^{2}[/tex]x = [tex]10^{5}[/tex] -> x = [tex]10^{3}[/tex]
Exercice 6:
A ->4x + (3x-1) - 3 = 8x - 2x + 4
-> 4x + 3x - 1 - 3 = 8x - 2x + 4
-> 7x - 4 = 6x + 4
-> 7 x - 6 x = 4 + 4
-> x = 8
B) -> 5x - (x - 4) =20
-> 5x - x + 4 = 20
-> 4x = 20 - 4
-> 4x = 16
->x = 4
C) -> 3 - (8x +1) = 2x- 4
-> 3 - 8x - 1 = 2x - 4
-> 2 - 8x = 2x - 4
-> - 8x - 2x = - 4 - 2
-> - 10x = - 6
-> 10x = 6
-> x = 0,6
D) ->( x - 2) + ( - x - 4) = 5x + ( - 2x + 16 )
-> x - 2 - x - 4 = 5x - 2x + 16
-> - 6 = -3x + 16
-> - 6 - 16 = - 3x
-> 24 = 3x
-> x = 8
Ps: je ne vois pas le E.
