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}