Resouds les equations suivantes a) (5x+1)(8-x)=0 b) (3x-1)+(7-x)=0 c) (8+3x)-(x+3)=0

a) 
(5x + 1)(8 - x) = 0
5x + 1 = 0 ou 8 - x = 0
5x = - 1 ou 8 = x
x = - 1/5 ou x = 8

S= {-1/5 ; 8}

b)
(3x - 1) + (7 - x) = 0
3x - 1 + 7 - x = 0
3x - x = - 7 + 1
2x = - 6
x = - 2/6
x = - 1/3 

S= {-1/3}

c)
(8 + 3x) - (x + 3) = 0
8 + 3x - x - 3 = 0
3x - x = - 8 + 3
2x = - 5
x = - 5/2

S= {-5/2}