Explications étape par étape:
1-L'image de g(x) est:
g(-3)=2(-3)²- 5(-3) +1
g(-3)=34
2-IJ/Sin90=KJ/Sin70=IK/sin20
9.2/1=KJ/0.94=IK/0.34
KJ=8.64
Ik=3.13
3-La vitesse est:
T=60×12. D=9km ou 9000m
T=720s
V=D/T
V=9000/720
V=12.5 m/s
4- Factorisons
A=(3x+1)²-81
A=(3x+1)²- 9²
A=(3x+1-9) (3x+1+9)
A=(3x-8) (3x+10)
5-Résolvons:
(2x-3) (8-x)=0
2x=3 ou 8-x=0
x=3/2 ou -x=-8; x=8
S={3/2;8}
