exercice 2
a)
5x-25=0
5x=25
x=25/5
x=5
b)
3x+1=7
3x=7-1
3x=6
x=6/3
x=2
c)
7x+13=-2
7x=-2-13
7x=-15
x=-15/7
d)
4x-3=0
4x=3
x=3/4
x=0.75
e)
4-3x=11
-3x=11-4
-3x=7
x=7/-3
x=-7/3
f)
5-x=7
-x=7-5
-x=2
x=-2
exercice 3
a)
3x=2x+5
3x-2x=5
x=5
b
4-5x=9x
-5x-9x=-4
-14x=-4
x=-4/14
x=4/14
c)
4x+2=x+11
4x-x=11-2
3x=9
x=9/3
x=3
d)
3x-7=-2x-9
3x+2x=-9+7
5x=-2
x=-2/5
x=-0.4
e)
5x-1=7x-1
5x-7x=-1+1
-2x=0
x=0
f)
3x-2+x=6+4x
4x-4x=6+2
cette équation n a pas de solution
exercice 4
a)
4x=3/5
(4x*5)/(1*5)=3/5
20x/5=3/5
20x=3
x=3/20
b)
2/3x=7
2/3x=(7*3)/(1*3)
2/3x=21/3
2x=21
x=21/3
x=7
c)
6/5x=-7/11
(6*11)/(5*11)x=(-7*5)/(11*5)
66/55x=-35/55
66x=-35
x=-35/66
d)
-7x=4/-3
(-7*(-3)/(1*(-3)x=4/-3
21/-3x=4/-3
21x=4
x=4/21
e)
-3/2x=5
-3/2x=(5*2)/(1*2)
-3/2x=10/2
-3x=10
x=10/-3
f)
-5/7x=-2/-3
(-5*3)/(7*3)x=(-2*(-7)/(-3*(-7)
-15/21x=14/24
-15x=14
x=14/-15
exercice 4
a)
2x=6
x=6/2
x=3
b)
3x=33
x=33/3
x=11
c)
9-4=x
x=5
d)
2x+6=0
2x=-6
x=-6/2
x=-3
e)
6-3x=9
-3x=9-6
-3x=3
x=3/-3
x=-1
f)
5x+2=x
5x-x=-2
4x=-2
x=-2/4
x=-1/2
g)
2(x+3)=x
2*x+2*3=x
2x+6=x
2x-x=-6
x=-6
h)
x+6=3(x+1)
x+6=3*x+3*1
x+6=3x+3
x-3x=3-6
-2x=-3
x=3/2
