Réponses

  • Utilisateur Brainly
2013-05-20T18:02:11+02:00

a)

2(x+1)=3(x-1)

2*x+2*1=3*x+3*(-1)

2x+2=3x-3

2x+2-3x=3x-3-3x

-1x+2=-3

-1x+2-2=-3-2

-1x=-5

x=-5/-1

x=5

 

b)

3(2-3y)=-(y-2)

3*2+3*(-3y)=-1*y-1*(-2)

6-9y=-1y+2

6-9y+1y=-1y+2+1y

6-8y=2

6-8y-6=2-6

-8y=-4

y=-4/-8

y=0.5

 

 

 

c) 

-2(a-1)=4(2a+1)

-2*a-2*(-1)=4*2a+4*1

-2a+2=6a+4

-2a+2-6a=6a+4-6a

-8a+2=4

-8a+2-2=4-2

-8a=2

a=2/-8

a=-0.25

 

voilà... :)