grafik fungsi f(x)=x^3+ax^2+bx+c hanya turun pada interval -5 < x < 3, nilai a+b =

f(x) = x³+ax²+bx+c
turun jika :
f'(x) < 0
3x²+2ax+b < 0 (1)
..
Interval : -5 < x < 3
x=-5 x=3
(x+5)(x-3) < 0
x²+2x-15 < 0
3x²+6x-45 < 0 (2)
...
3x²+2ax+b = 3x²+6x-45
• 2a = 6 → a = 3
• b = -45
maka, a + b = 3 + (-45) = -42

Maaf jika salah..