bonjour
1) (x - 1)(x + 3) = (x + 2)(x – 5)
x² + 3x - x - 3 = x² - 5 x + 2 x - 10
x² - x² + 2 x + 5 x - 2 x = - 10 + 3
5 x = - 7
x = - 7/5
2) -5(x + 2)(3x – 5) +15(x2 - 1) =0
- 5 ( 3 x² - 5 x + 6 x - 10 ) + 15 x² - 15 = 0
- 5 ( 3 x² + x - 10 ) + 15 x² - 15 = 0
- 15 x² - 5 x + 50 + 15 x² - 15 = 0
- 1 5x² + 15 x² - 5 x = - 50 + 15
- 5 x = - 35
x = 7
3) 4(x2 + 1) – 2(2x - 5)(x + 2) =0
4 x² + 4 - 2 ( 2 x² + 4 x - 5 x - 10 ) = 0
4 x² + 4 - 4 x² - 8 x + 10 x + 20 = 0
4 x² - 4 x² + 2 x = - 20 - 4
2 x = - 24
x = - 12
