Réponse :
bonjour
A = 2x - 2( x-3) - 5
= 2x - 2x + 6 - 5
= 1
C = ( 2x - 3)² - 2 ( 2x - 3)
= ( 2x - 3) ( ( 2x - 3) - 2 )
= ( 2x - 3) ( 2x - 3 - 2 )
= ( 2x - 3)( 2x - 5 )
B - A
= (x + ( 2 + x ) ( x - 1 ) + 2³) - (2x - 2( x-3) - 5)
= (x + 2x - 2 + x² - x + 8) - (2x - 2x + 6 - 5)
= (x² + 2x + 6) - 1
= x² + 2x + 5
avec x = -1
B = x² + 2x + 6
B = (-1)² + 2×(-1) + 6
B = 1 - 2 + 6
B = 5
voila :)
