N.b., this is copied from an answer I wrote for someone else.Thinking about the graph of y, the rate of change is zero whenever there is an extremum.
First, differentiate y.

Next, find the zeros of y' by factoring.

Now, we substitute these x-values into the
original equation to find the coordinates.
Discriminant = b^2 - 4ac, where a, b and c come from the form of the quadratic equation as ax^2 + bx + c
Discriminant = (4)^2 - 4(1)(5)
= 16 - 20
= -4
-4 < 0, therefor there are no roots
(If the discriminant = 0, then there is one root
If the discriminant > 0, there are two roots, and if it is a perfect square (eg. 4, 9, 16, etc.) then there are two rational roots
If the discriminant < 0, there are no roots)
Answer:
answer is 11.9...... have a good day