Bonjour,
Résoudre ces équations :
x² + 4 = 20
x² + 4 - 20 = 0
(x - 4) (x + 4) = 0
x - 4 = 0 ou x + 4 = 0
x = 4 x = - 4
2x² + 5 = 23
2x² + 5 - 23 = 0
2x² - 18 = 0
2 (x - 3) (x + 8) = 0
x - 3 = 0 ou x + 8 = 0
x = 3 x = - 8
x²- 100 = 5³
x² - 100 - 5³ = 0
x² - 100 - 125 = 0
x² - 225 = 0
(x - 15) (x + 15) 0
x - 15 = 0 ou x + 15 = 0
x = 15 x = - 15
7x² - 6 = 5x² 66 --> Incompréhensible...