Bonjour,
a)
(3/4)*x=5 <=> x=5*(4/3)
<=> x=20/3
b)
4x-3=11 <=> 4x=11+3
<=> x=14/4=7/2
c)
7-8x=56 <=> 8x=7-56
<=> x=-49/8
d)
6x-4=3x+14 <=> 6x-3x=14+4
<=> 3x=18
<=> x=18/3=6
e)
9-2x=11+4x <=> 9-11=4x+2x
<=> -2=6x
<=> x=-2/6=-1/3
f)
5(x-3)-3x+7=5x-15-3x+7
=2x-8
Donc :
5(x-3)-3x+7=9 <=> 2x-8=9
<=> 2x=9+8
<=> x=17/2