Pourrez-vous m’aider à faire ce dm, j’ai essayer de la faire mais je ne comprend rien.

Réponse :

Bonjour,

Explications étape par étape

Ex1 :

A = 4/7-2 / 2-11/4

A = 4/7 - 14/7 / 8/4 - 11/4

A = -10/7 / -3/4

A = -10/7 × (-4)/3

A = 40/21

B = 2 × (10^3)^4 × 10^-8 / 40 × 10^-2 × 1/5

B = 2/40 × 1/5 × 10^12 × 10^-8/10^-2

B = 2/40/5 × 10^((12+(-8))/10^-2

B = 2/8 × 10 ^4/10^-2

B = 1/4 × 10^4-(-2)

B = 1/4 × 10^6

B = 0.25 × 10^6

B = 2.5 × 10^5

C = (2/5 / 8/15) / (4/7 / 5/21)

C = (2/5 × 15/8) / (4/7 × 21/5)

C = (2×5×3 /5×4×2) / (4×7×3 /7×5)

C = (3/4) / (12/5)

C = 3/4 × 5/12

C = 3×5 / 4×4×3

C = 5/16

C = 0.3125

Ex 2 :

1) développer et réduire D

D = (2x-3)^2 - 3(2x -3)

D = 4x^2 - 2 ×2x×3+9 -6x+9

D = 4x^2 - 18x + 18

2) factoriser D

D = (2x-3)(2x-3) - 3(2x-3)

D = (2x-3)[(2x-3)-3]

D = (2x-3)(2x-6)

3) calculer D pour x = 2

D = (2x-3)(2x-6)

D = ( 2 × 2 -3)(2 × 2 -6)

D = (4-3)(4-6)

D = 1 × (-2)

D = -2

4) D = 0

(2x -3)(2x-6) = 0

2x - 3 = 0 ou 2x - 6 = 0

2x = 3 ou 2x = 6

X = 3/2 ou x = 6/2 = 3

S = {3/2 ; 3}