oit l'expressions A= (3x-1)² - (x+2) (3x-1) a) développer A. b) Calculer l'expression A pour x =-2 puis pour x = [tex] \frac{2}{3} [/tex] c) Verifier que l'expr

A= (3x-1)² - (x+2) (3x-1)
a = 9x²-6x+1 -(3x²-x+6x-2)
a = 9x²-6x+1 -3x²+x-6x+2
a = 6x²-11x +3

pour x = 2

a =6x²-11x+3
a =6(2)² -11(2) +3
a = 6(4) -22+3
a =24 -22 +3
a =5

pour x = 2/3

a =6(2/3)² -11(2/3) +3
a= 6(4/9) -22/3 +3
a =8/3 -22/3 +3
a = 8/3 -22/3 +9/3
a= - 5/3

A= (3x-1)² - (x+2) (3x-1)
(3x-1)(3x-1-x-2)
(3x-1)(2x-3)

a)
A= (3x-1)² - (x+2) (3x-1)
= 9x²-6x+1 -(3x²-x+6x-2)
= 9x²-6x+1 -3x²+x-6x+2
= 6x²-11x +3
b)
A=6x²-11x+3
=6(2)² -11(2) +3
= 6(4) -22+3
=24 -22 +3
=5
A =6(2/3)² -11(2/3) +3
= 6(4/9) -22/3 +3
=8/3 -22/3 +3
= 8/3 -22/3 +9/3
= - 5/3
c)
A= (3x-1)² - (x+2) (3x-1)
=(3x-1)(3x-1-x-2)
=(3x-1)(2x-3)