Sagot :
Le signe moins devant (-3*x+-12) change tous les signes entre parenthèses.
=(3*x+12)+-7*x
= 3*x+12+-7*x | ajouter 3*x et -7*x
= -4+-7*x+12
=(3*x+12)+-7*x
= 3*x+12+-7*x | ajouter 3*x et -7*x
= -4+-7*x+12
-(-3x-12)-7= -3x+26
(3x+12)7 = -3x+26
21x + 84 = -3x +26
21x + 3x =26 - 84
24x = 58
x = [tex]\frac{84}{58}[/tex] = (84/2)(/58/2)
x= [tex]\frac{42}{29}[/tex]