Question 1037240
A is a cubic, degree-three function, and B is a quadratic function.


{{{3x^2-10x-8=0}}}
{{{(3x+2)(x-4)=0}}}
{{{system(x=-2/3,or,x=4)}}}


How does the derivative look for A?
{{{x^3-5x^2-8x+40}}}
{{{dA/dx=3x^2-10x-8}}}, and you already know the zeros for this  because it is the same function expression as B(x).


The slope of A is 0, both at x=-2/3, and at x=4.
That means A has extreme points  (highest or lowest values) at those x values.
Which type of extreme, you can check through second derivative and testing points near the extremes.  


Just to cut out some of the work,  Here is A(x).
{{{graph(300,300,-4,6,-8,45,x^3-5x^2-8x+40)}}}