Bonjour,
Développer:
A(x)= 1+2x+x²-(3x²+2x+3x+2)= x²+2x+1-3x²-5x-2= - 2x²-3x-1 .
Factoriser:
A(x)= (x+1)(x+1-3x-2)= (x+1)(-2x-1)= - (x+1)(2x+1).
Résoudre:
- (x+1)(2x+1) ≤ 0 ⇔ (x+1)(-2x-1) ≤ 0
x= -1
x= - 1/2
S= ] - ∞; - 1 ] U [ - 1/2; + ∞ [ .
Résoudre:
- 2x²-3x-1 ≥ - 1
- 2x²-3x-1 +1 ≥ 0
- 2x²-3x ≥ 0
-x(2x+3) ≥ 0
x= 0
x= - 3/2
S= [ - 3/2; 0 ] .
