Salut
A = ( 2b + 3 ) ( 4b – 1 ) + ( 2b + 3 ) ( -b + 5 )
repérage du facteur commun : (2b+3)
= (2b+3)[(4b-1)+(-b+5)]
= (2b+3)(4b-b-1+5)
= (2b+3)(3b+4)
B = ( 4y – 2 ) ( 3 – 2y ) – ( 7y – 1 ) ( 3 – 2y )
repérage du facteur commun : (3-2y)
= (3-2y)[(4y-2)-(7y-1)]
= (3-2y)(4y-7y-2+1)
= (3-2y)(-3y-1)
= -(3-2y)(3y+1)
C = ( x + 3 )² + ( 2x – 5 ) ( x + 3 )
= (x+3)(x+3) + (2x-5)(x+3)
facteur commun : (x+3)
= (x+3)[(x+3)+(2x-5)]
= (x+3)(x+2x+3-5)
= (x+3)(3x-2)
identité remarquable : a²-b² = (a+b)(a-b)
donc :
D = c² – 16
= c² - 4²
= (c+4)(c-4)
E = 100a² - 25
= (10a)² - 5²
= (10a+5)(10a-5)
