bjr
E = ( 2 x + 3 )² – ( 2 x + 3 ) ( x – 2 )
= (2x)² + 2*2x*3 + 3² - (2x*x + 2x*(-2) + 3*x + 3*(-2))
= 4x² + 12x + 9 - (2x² - 4x + 3x - 6)
= 4x² + 12x + 9 - 2x² + x + 6
= 2x² + 13x + 15
E = ( 2 x + 3 )² – ( 2 x + 3 ) ( x – 2 )
= ( 2 x + 3 ) (2x + 3) – ( 2 x + 3 ) ( x – 2 )
= (2x+3) (2x+3 - (x-2))
= (2x+3) (2x + 3 -x + 2)
= (2x+3) (x + 5)
E = 0
si 2x + 3 = 0 => x = -3/2
ou si x + 5 = 0 => x = -5
S = {-5 ; - 1,5}
