Répondre :
A=(X+1)² - (X+7)²
=(x+1-x+7)(x+1+x-7)
=8(2x-6)
=16(x-3)
B=(2X+5)² - (2X+3)²
=(2x+5-2x-3)(2x+5+2x+3)
=2(4x+8)
=8(x+2)
C=(4X-7)² - (3X+5)²
=(4x-7-3x-5)(4x-7+3x+5)
=(x-12)(7x-2)
D=(2+5X)² - (4X-1)²
=(2+5x-4x+1)(2+5x+4x-1)
=(x+3)(9x+1)
=(x+1-x+7)(x+1+x-7)
=8(2x-6)
=16(x-3)
B=(2X+5)² - (2X+3)²
=(2x+5-2x-3)(2x+5+2x+3)
=2(4x+8)
=8(x+2)
C=(4X-7)² - (3X+5)²
=(4x-7-3x-5)(4x-7+3x+5)
=(x-12)(7x-2)
D=(2+5X)² - (4X-1)²
=(2+5x-4x+1)(2+5x+4x-1)
=(x+3)(9x+1)