Réponse :

Bonjour,

Explications étape par étape

Ex1

(3x + 2/3)^2 = 9x^2 + 2*3x*2/3+(2/3)^2

=9x^2 + 12x/3 +4/9

= 9x^2 +4x + 4/9

ex2

(X-5)^2 = x^2 - 2*x*5+25

= x^2 - 10x +25

(5-3x)^2 = 25 - 2*5*3x+9x^2

= 25 - 30x + 9x^2

= 9x^2-30x+25

(4x-5/8)^2 = 16x^2 - 2*4x*5/8+(5/8)^2

= 16x^2 - 40x/8+25/64

= 16x^2 -5x +25/64

ex 3

(3x-5)(3x+5) = 9x^2-25

(2x+5)(5-2x) = -4x^2 + 25

ex4

A(x) = (6x-4)^2+(9x-3)(5-4x)

A(x) = 36x^2-2*6x*4+16+45x-36x^2-15+12x

A(x) = 9x + 1

A(-2) = 9*(-2) + 1

A(-2) = -18 + 1

A(-2) = -17

Je te laisse reposter l'exercice 5