Is (-1, -4) a solution to a equation y=6x_ -2?

The center of the circumscribed circle lies on line segment and the longest side of the triangle is equal to the of the circle.

How to do this , and can some one explain

The graph of a function f(x)=(x+2)(x-4). which describes all of the values for which the graph is negative and increasing? all real values of x where x< -2 all real values of x where -2