Réponse :
Explications étape par étape :
Bonsoir
1)
sur [-20;20]
f(x) = - 3 x + 7
x = - 15
f(- 15 ) = 3 (-15) + 7 = - 45 + 7 = -38
x = 5
f(5) = - 3 (5) + 7= -15 + 7 = - 8
x -20 -15 -10 - 5 0 5 10 15 20
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f(x) 67 52 37 22 7 - 8 -23 -38 -53
2)
sur sur [-15;15]
f(x) = x²/2 + 4
x - 15 - 10 - 5 0 2 5 10 15
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f(x) 117 54 17 4 6 17 54 117
sur [-20;20]
f(x) = x/(x+30)
f(-20) = (-20)/(-20+30) = (-20)/(10) = -2
f(-5) =(-5)/(-+30)= (-5)/(25)= -1/5 = -0.2
f(0) = 0
f(15) = (15)/(15+30) = 15/45= 1/3 ≈ 0.33
f(20) = (20)/(20+30) = (20)/(50) = 2/5 = 0.4
