Réponse :

Explications étape par étape

Bonjour

2x + 5 = -3

2x = -3 - 5

x = -8/2

x = -4

3x + 8 = 3 - 2x

3x - 2x = 3 - 8

x = -5

7x = 8 - x

7x + x = 8

8x = 8

x = 8/8

x = 1

5(x + 3) = 2x - 6

5x + 15 = 2x - 6

5x - 2x = -15 - 6

3x = -21

x = -21/3

x = -7

x^2 + 4 = 5x

x^2 - 5x + 4 = 0

x^2 - 2 * x * 5/2 + (5/2)^2 - (5/2)^2 + 4 = 0

(x - 5/2)^2 - 25/4 + 16/4 = 0

(x + 5/2)^2 - 9/4 = 0

(x + 5/2)^2 - (3/2)^2 = 0

(x + 5/2 - 3/2)(x + 5/2 + 3/2) = 0

(x + 2/2)(x + 8/2) = 0

(x + 1)(x + 4) = 0

x + 1 = 0 ou x + 4 = 0

x = -1 ou x = -4

2(3x + 2) = 4 + 6x

6x + 4 = 4 + 6x

6x - 6x = 4 - 4

0 = 0

Vrai quelque soit x