bonjour
a = 3 ( y - x )
b = 5 x ( 2 - x)
c = ( 5 x + 1 ) ( 2 x + 3 )
d = ( x - 3 ) ( 2 x - 5 + 4 x ) = ( x - 3 ) ( 6 x - 5 )
e = ( 4 x - 7 ) ( x + 2 - 3 x + 5 ) = ( 4 x - 7 ) ( - 2 x + 7 )
