Réponse :

Explications étape par étape

Bonjour,

a)

4+21 = 8x -3x

25 = 5x

x= 25/5 = 5

b)

1+80 = 7x +2x

81 = 9x

x = 81/9 = 9

c)

-3-3 = 5x -2x

-6 = 3x

x= -6/3 = -2

d)

5x-3x = -5 +3

2x = -2

x= -2/2 = -1

A)3x+4=8x-21

3x-8x=-21-4

-5x=-25

-5x/-5=-25/-5

X=5

B)-2x+1=7x-80

-2x-7x=-80-1

-9x=-81

-9x/-9=-81/-9

X=9

C)2x-3=5x+3

2x-5x=3+3

-3x=6

-3x/-3=6/-3

X=-2

D)5x-3=3x-5

5x-3x=-5+3

2x=-2

2x/2=-2/2

X=-1