bonjour,
devoir bcp trop long, je fais le 2, il faudrait refaire 3 messages pour les autres
fonction affine = ax+b
f(-3) = -13→-3a+b = -13
f(6) = 14 →6a+b = 14
3a+b = -13
6a+b = 14
on résous par substituion (ça s'apprend en 3eme!!!!!!!!!)
3a+b = -13
b = -3a-13
6a+(-3a-13) = 14
6a-3a-13 =14
3a = 14+13
a = 9
6a+b = 14
54+b = 14
b = 14-54
= -40
f(x) = 9x-40
g(1) = 3 → a+b = 3
g(7) = 6→7a+b = 6
a+b = 3
7a+b = 6
-1(a+b) = 3
7a+b = 6
-a-b = -3
7a+b = 6
6a = 3
a = 3/6 =1/2
a+b = 3
1/2+b =3
b = 3-1/2
= 5/2
g(x) = x/2 +5/2
