Exercice 7: 1) Factoriser: C = x2 - 7 D = 25x2 - 1 B = 81 - 4t? A = 18x? - 45 Bonjour est-ce que quelqu’un peut m aider a factoriser les expressions s’il vous p

Bonjour,

C = x² - 7: (x-√7)(x+√7)

D = 25x² - 1 =(5x-1) (5x+1)

B = 81 - 4t² : (9-2t) (9+2t)

A = 18x - 45 = 3( 6x- 15)

Réponse :

on factorise:

C = x² - 7  

C= (x*x) - (√7 * √7)                        on utilise :a² -b² = (a -b)(a+b)

C = (x-√7)(x +√7)

D = 25x² - 1

D = (5x)² - (1)²

D = (5x - 1)(5x +1)

B = 81 - 4t²

B = 9² - (2t)²

B = (9-2t)(9+2t)

A = 18x² - 45

A = (3*2*2*x*x) - (3*3*5)

A = ((√3)² * 2² *x²) - (3² *(√5)²)

A = (2√3x)² - (3√5)²

A = (2√3 - 3√5)(2√3 + 3√5)