Juste le 88 a faire svp et ensuite il faut le développer et le vérifier en remplaçant x par 1

Bonjour

La prochaine fois à toi de les recopier à la main !

A = 4x - (2 - x) (x + 3)

A = 4x - (2x + 6 - x² - 3x)

A = 4x - 2x - 6 + x² + 3x

A = x² + 5x - 6

B = 3 (x - 2) (2x + 5)

B = 3 (2x² + 5x - 4x - 10)

B = 6x² + 15x - 12x - 30

B = 6x² + 3x - 30

C = 5x - (x + 1) (6x - 2)

C = 5x - (6x² - 2x + 6x - 2)

C = 5x - 6x² + 2x - 6x + 2

C = - 6x² + x + 2

D = x (x - 1) (x + 2)

D = x (x² + 2x - x - 2)

D = x³ + 2x² - x² - 2x

D = x³  + x² - 2x.

Remplacer x par 1

A = x² + 5x - 6

A = 1² + 5 * 1 - 6

A = 1 + 5 - 6

A = 6 - 6

A = 0

B = 6x² + 3x - 30

B = 6 * 1² + 3 * 1 - 30

B = 6 * 1 + 3 - 30

B = 7 - 27

B = - 20

C = - 6x² + x + 2

C = - 6 * 1² + 1 + 2

C = - 6 * 1 + 3

C = - 6 + 3

C = - 3

D = x³  + x² - 2x.

D = 1³ + 1² - 2 * 1

D = 1 + 1 - 2

D = 2 - 2

D = 0.

Réponse :

Bonjour,

[tex]A=4x-(2-x)(x+3)\\=4x-(2x + 6 -x^2 - 3x)\\= 4x - 2x - 6 + x^2 + 3x\\= x^2 + 5x - 6\\\\[/tex]

Vérification:

Pour x = 1

4 × 1 – (2 – 1) × (1 + 3)

= 4 – 1 × 4

= 4 – 4

= 0

1² + 5 × 1 – 6

= 1 + 5 – 6

= 6 – 6

= 0

[tex]B=3(x - 2)(2x + 5)\\= (3x-6)(2x + 5)\\= 6x^2+15x-12x - 30\\= 6x^2+3x-30[/tex]

Vérification:

Pour x = 1

3 × (1 – 2) × (2 × 1 + 5)

= 3 × (–1) × (2 + 5)

= –3 × 7

= – 21

6 × 1² + 3 × 1 – 30

= 6 × 1 + 3 – 30

= 6 + 3 – 30

= 9 – 30

= –21

[tex]C=5x - (x + 1)(6x-2)\\= 5x-(6x^2-2x+6x-2)\\= 5x-6x^2+2x-6x+2\\= -6x^2+x+2\\[/tex]

Vérification:

Pour x = 1

5 × 1 – (1 + 1) × (6 × 1 – 2)

= 5 – 2 × (6 – 2)

= 5 – 2 × 4

= 5 – 8

= –3

–6 × 1² + 1 + 2

= –6 × 1 + 3

= –6 + 3

= –3

[tex]D=x(x-1)(x+2)\\= (x^2-x)(x + 2)\\= x^3 + 2x^2 - x^2 - 2x\\= x^3 + x^2 - 2x[/tex]

Vérification:

Pour x = 1

1 × (1 – 1) × (1 + 2)

= 1 × 0 × 3

= 0

1³ + 1² – 2 × 1

= 1 + 1 – 2

= 2 – 2

= 0