Resoudre les équations suivantes en mettant bien les étapes de calcus; a) x/3+3=x-5 b)a/3-5=a/5-3 c)2t/3+4=-2t-7 d)7b/3-4=-5b/7+13

bonsoir

a) x/3 + 3 = x - 5

tu mets sous dénominateur 3 
x + 9 = 3 x - 15
x - 3 x = - 15 - 9
- 2 x = - 24
x = 12

b) a/3 - 5 = a / 5 - 3
    5 a - 75 = 3 a - 45
    5 a - 3 a = - 45 + 75
    2 a = 30
      a = 15

c) 2 t + 12 = - 6 t - 21
   2 t + 6 t = - 21 - 12
   8 t = - 33
     t = - 33/8

d) 49 b - 84 = - 15 b + 273
    49 b + 15 b = 273 + 84
    64 b = 357
        b = 357/64

a) x/3+3=x-5

 x/3 - x= - 5 -3
 (x-3x) / 3 = -8
-2x / 3 = - 8
-2x = -8 * 3
-2x = -24
x = 24/2
x = 12

 
b)a/3-5 = a/5 - 3
a/3- a/5 = 5-3
(5a -3a) / 15 = 2
2a / 15 = 2
2a = 2*15
2a = 30
a = 30/2
a = 15


c)2t/3+4 = -2t - 7
2t/3 +2t = - 4 - 7
(2t +6t )/3 = - 11
8t / 3 = -11
8t= -11 * 3
8t = -33
t= -33/8


d)7b/3-4 = -5b/7+13
7b/3  +5b/7 =+4 +13
(49b +15b) /21 = 17
64b /21 = 17
64b = 17 *21
64b = 357
b = 357/64