Bonsoir,

Il suffit de faire passer les x à gauche et les nombres entiers à droite

a)

3x + 5 = 4x - 7

3x = 4x - 7 - 5

3x - 4x = -12

-x = -12

x = 12

b)

2x - 9 = 8x + 3

2x = 8x + 3 + 9

-6x = 12

-x = 2

x = -2

c)

-2x + 3 = 3x - 1

-2x = 3x - 1 - 3

-2x - 3x = -4

-5x = -4

-x = -4/5

x = 4/5

d)

5 - 2x = x

-3x = -5

x = 5/3

e)

1 + (3/10)x = 4 - (2/5)x

(3/10)x = 3 - (2/5)x

(3/10)x + (2/5)x = 3

(3/10)x + (4/10)x = 3

(7/10)x = 3

x = 3/(7/10)

x = 3 × 10/7

x = 30/7

f)

x^7 + 3x - 2 = 7x + 4 + x^7

3x - 2 = 7x + 4

-4x = 6

-x = 6/4

x = -6/4