Bonjour

5 + 4x = 9x

5 + 4 * 10 = 9 * 10

5 + 40 = 90

45 ≠ 90

3 * (2x + 5) = 6x + 5

3 * (2 * 10 + 5) = 6 * 10 + 5

3 * (20 + 5) = 60 + 5

60 + 15 = 65

75 ≠ 65

2x² = 4x

2 * 10² = 4 * 10

2 * 100 = 40

200 ≠ 40

x² = - 100

10² = - 100

100 ≠ - 100

3 * (2x + 5) = 10x - 25

3 * (2 * 10 + 5) = 10 * 10 - 25

3 * (20 + 5) = 100 - 25

60 + 15 = 75

75 = 75 → Vraie

5 + 4x = 9x - 45

5 + 4 * 10 = 9 * 10 - 45

5 + 20 = 90 - 45

25 ≠ 45

x² - 100 = 0

10² - 100 = 0

100 - 100 = 0

0 = 0 → Vraie

3 * (2x + 5) = 6x + 15

3 * (2 * 10 + 5) = 6 * 10 + 15

3 * (20 + 5) = 60 + 15

3 * 25 = 75

75 = 75 → Vraie.