vraiment besoins d'aide.. svppp !

Salut,

E = (x+2)(x-3) + (x-3)

a)
E = (x+2)(x-3) + (x-3)
E = x² - 3x + 2x - 6 + x - 3
E = x² -9

b)

E avec x = √2

E = (√2)² - 9 = 2 - 9 = -7

c)

E = (x+2)(x-3) + (x-3)
E = (x+2)(x-3) + (x-3) * 1
E = (x-3)[x+2+1)]
E = (x-3)(x+3)

d)

x² - 9 = 0
x² - 3² = 0
(x-3)(x+3) = 0
x - 3 = 0
x = 3

x + 3 = 0
x = -3

S = {-3; 3}

Bonne soirée !