Bonjour,
on sait que 4 = 2²
et que a²-b²=(a+b)(a-b)
donc : (-5x-2)²-4 = (-5x-2)² - 2²
= [(-5x-2+2)(-5x-2-2)]
= (-5x)(-5x-4)
Factoriser:
(-5x-2)²-4= (-5x-2)² -2²= (-5x-2-2)(-5x-2+2)= (-5x-4)(-5x)= 5x(5x+4)
