Answer:
5 < x < ∞
-∞ < x < 0
2 < x < ∞
Step-by-step explanation:
Given function is + 3
+ 1.
To, Calculate where the function is increasing or decreasing,
we have to calculate the derivative of the function,
so,
f'(x) = -3 + 6x.
Equating the f'(x)= 0 , we get
x(-3x + 6) = 0
So, f'(x) will be zero at x = 0 and x = 2.
f(x) will be decreasing in the interval where f'(x) will be negative.
now as the coefficient of f'(x) is negative it will be negative between
the interval -∞ < x < 0 and 2 < x < ∞.
Options which lie in these intervals only are
5 < x < ∞
-∞ < x < 0
2 < x < ∞
