f(x)=−3x2+2x+5 is concave at
-2
In the interval in which a function is concave, the value of the derivative f’(x) keeps on reducing. So we can say f”(x) will be less than zero.
Let’s double differentiate the given function.
f(x)=−3x2+2x+5
f’(x) = - 6x + 2
f”(x) = - 6
Here, we get the second derivative to be negative for all the values of x. So we can say that the function is concave at all the points given.