Mrc a celui qui m’aide

Bonjour,

2)

A = 7/3 - 4/3 : 8/5

A = 7/3 - 4/3 x 5/8

A = 7/3 - 20/24

A = (7 x 8) / (3 x 8) - 20/24

A = 56/24 - 20/24

A = 36/24

A = (12 x 3) / (12 x 2)

A = 3/2

B = (4/7 + 2/3) : 13/14

B = [(4 x 3) / (7 x 3) + (2 x 7) / (3 x 7)] : 13/14

B = (12/21 + 14/21) : 13/14

B = 26/21 x 14/13

B = 364/273

B = (91 x 4) / (91 x 3)

B = 4/3.

3)

A (x) = (x + 3) (5x + 1)

B (x) = x² + 4x - 5

1- Démontrer que A (- 2) = B (- 2)

A (x) = (x + 3) (5x + 1)

A (- 2) = (- 2 + 3) (5 * - 2 + 1)

A (- 2) = 1 * (- 10 + 1)

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

A (- 2) = - 9

B (x) = x² + 4x - 5

B (- 2) = - 2² + 4 * - 2 - 5

B (- 2) = 4 - 8 - 5

B (- 2) = 4 - 13

B (- 2) = - 9.

2- A et B toujours égales ? Rémus a-t-il raison ?

A (x) = (x + 3) (5x + 1)

A (x) = 5x² + x + 15x + 3

A (x) = 5x² + 16x + 3

B (x) = x² + 4x - 5

A = B

Rémus a tort.