bjr
a) soit x le nombre choisi
x → x + 3 puis x +3 → (x +3)(-5)
x |----------------------------------> - 5(x + 3)
f
f(x) = -5(x + 3)
b)
f(-3) = -5(-3 + 3) = -5*0 = 0
f(4) = -5(4 + 3) = - 5*7 = -35
f(-5) = -5*(-5 + 3) = -5*(-2) = 10
c)
pour quelle valeur de x a-t-on f(x) = - 12
f(x) = - 12
-5(x + 3) = - 12
x + 3 = -12/(-5)
x+ 3 = 12/5
x = 12/5 - 3
x = 12/5 - 15/5
x = -3/5
