bonjour
A (x) = ( 1 + x ) ² - ( 3 x + 2 ) ( x + 1 )
1 ) a (x) = 1 + 2 x + x² - ( 3 x² + 3 x + 2 x + 2 )
A ( x) = x² + 2 x + 1 - 3 x² - 5 x - 2
A (x) = - 2 x² - 3 x - 1
2 ) A (x ) = ( x + 1 ) ( x + 1 - 3 x - 2 )
A (x) = ( x + 1 ) ( - 2 x - 1 )
A ( x) < 0
x + 1 < 0
x < - 1
ou bien
- 2 x - 1 < 0
- 2 x < 1
x > - 1 /2
a(x) ≥ - 1
- 2 x - 1 + 1 ≥ 0
- 2 x ≥ 0
x ≥ 0
x + 1 ≥ - 1
x ≥ - 1 - 1
x ≥ - 2
