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Bonjour, est ce que quelqu’un pourrait m’aider pour ce devoir svp ?

Résoudre les équations suivantes (en détaillant les calculs)

a) 7x + 9 = 11
b) 5 - 3x = 12
c) 4x - 8 = 14
d) - x - 11 = -5
e) 2x - 2 = 8x - 8
f) 3x - 8 = 7 x + 2
g) 11 + x = 7 - 13x


Répondre :

Bonsoir

a) 7x + 9 = 11
<=> 7x = 11 - 9
<=> 7x = 2
<=> x = 2/7

b) 5 - 3x = 12
<=> -3x = 12 - 5
<=> -3x = 7
<=> x = 7/(-3)
<=> x = -7/3


c) 4x - 8 = 14
<=> 4x = 14 + 8
<=> 4x = 22
<=> x = 22/4
<=> x = 11/2

d) -x - 11 = -5
<=> -x = -5 + 11
<=> -x = 6
<=> x = -6

e) 2x - 2 = 8x - 8
<=> 2x = 8x - 8 + 2
<=> 2x = 8x - 6
<=> 2x - 8x = -6
<=> -6x = -6
<=> x = -6/(-6)
<=> x = 6/6
<=> x = 1

f) 3x - 8 = 7x + 2
<=> 3x = 7x + 2 + 8
<=> 3x = 7x + 10
<=> 3x - 7x = 10
<=> -4x = 10
<=> x = 10/(-4)
<=> x = -5/2

g) 11 + x = 7 - 13x
<=> 11 + x + 13x = 7
<=> 11 + 14x = 7
<=> 14x = 7 - 11
<=> 14x = -4
<=> x = -4/14
<=> x = -2/7

VOilà j'espère avoir pu t'aider ^^



Bonjour,
a) 7x+9=11
7x=11-9
7x=2
7x/7=2/7
x=2/7
b)5-3x=12
-3x=12-5
-3x=7
-3x/-3=7/-3
x=7/-3
c)4x-8=14
4x=14+8
4x=6
4x/4=6/4
x=3/2
d)-x-11=-5
-x=-5+11
-x=6
-x/-1=6/-1
x=-6
e)2x-2=8x-8
2x-8x=-8+2
6x=-6
6x/6=-6/6
X=-1
f)3x-8=7x+2
3x-7x=2+8
-4x=10
-4x/-4=10/-4
X=5/-2
g)11+x=7-13x
X+13x=7-11
14x=-4
14x/14=-4/14
X=-2/7
Voilà j'espère que ça ta aider