Réponse:

1)

f(7)=189,4

f(10)=400

f(15)=75

2a) Sur [7; 15 ] :

f'(x) = 1,3×3x²-58,5×2x+780

f'(x) = 3,9x²-117x+780

2b)

3,9(x-10)(x-20) =

3,9(x²-10x-20x+200) =

3,9x² - 117x+780 =

f'(x)

x |7 10 15

3,9 | + +

x-10 - 0 +

x-20 - -

f'(x) + 0 -

f ↗ 400 ↘

189,4 75