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
