Sagot :
B = 121 - (5x + 7)
B = 121 - 5x -7
B = 114 -5x
A = 5x(7x-5) - (7x-5)(9x+2)
A = 35x² - 25x - ( 63x²+14x-45x-10)
A = 35x² - 25x - 63x² -14x +45x +10
A = -28x²+6x+10
A = -2(2x+1)(7x-5)
Réponse :
factoriser B = 121 - (5 x + 7)² = 11² - (5 x + 7)² identité remarquable
= (11 + 5 x + 7)(11 - 5 x - 7)
= (5 x + 18)(4 - 5 x)
factoriser A = 5 x(7 x - 5) - (7 x - 5)(9 x + 2)
= (7 x - 5)(5 x - 9 x - 2)
= (7 x - 5)(- 4 x - 2)
Explications étape par étape :