Bonjour j aurais besoin d aide svp Developper a) (x-7)(x+7) b) (3x+1) c) (2x+5)(2x-5) d) (4-x)(4+x)

Réponse:

Bonjour,

a) (x-7)(x+7)

=x*x+x*7+(-7)*x+(-7)*7

= x²+7x-7x-49

=x²-49

b) (3x+1)

=3x+1

c) (2x+5)(2x-5)

=2x*2x+2x*(-5)+5*2x+5*(-5)

=4x²+(-10x)+10x+(-25)

=4x²-25

d) (4-x)(4+x)

=4*4+4*x+(-x)*4+(-x)*x

=8+4x-4x-x²

=x²+8

*=signe de multiplication.