Réponse :
ex1
a) faux
b) vrai
c) vrai
d) faux
e) faux
ex2 Développer
a) 2 x(4 x - 7) = 8 x² - 14 x
b) 7 x²(5+3 x) = 35 x² + 21 x³
= 21 x³ + 35 x²
ex3 Developper
a) (2 x - 5)(3 x + 4) = 6 x² + 8 x - 15 x - 20
= 6 x² - 7 x - 20
b) (5 x - 2)(4 x - 6) = 20 x² - 30 x - 8 x + 12
= 20 x² - 38 x + 12
Ex4 Factoriser
a) 5 x² - 20 = 5(x²- 4)
= 5(x - 2)(x + 2)
b) 18 x + 12 = 6(3 x + 2)
c) - 8 x + 24 = 8(- x + 3)
ex5 Factoriser
A = (3 x - 7)(2 x + 3) + (3 x - 7)(4 x - 9)
= (3 x - 7)(2 x + 3 + 4 x - 9)
= (3 x - 7)(6 x - 6) = 6(x - 1)(3 x - 7)
B = (5 x + 8)(6 x - 7) - (11 x - 5)(5 x + 8)
= (5 x + 8)(6 x - 7 - 11 x + 5)
= (5 x + 8)(- 5 x - 2)
Explications étape par étape
