Question 1183440
.
<pre>

The x-coordinate of the vertex is exactly half way between the roots  h = {{{((-3) + 3)/2}}} = {{{0/2}}} = 0.


Hence, the vertex is located at  (0,-18).


It means that the value of the quadratic polynomial at x = 0 is -18.


So, we substitute x= 0 into the polynomial and equate it to -18


    c*(0-3)*(0+3 = c*(-9) = -18,

or

    -9c = -18.


It gives the value of "c"   c = {{{(-18)/(-9)}}} = 2.      <U>ANSWER</U>


                See the plot below


    {{{graph(300,300,-10,10,-20,20,2(x-3)(x+3))}}}



              Plot y = 2(x-3)*(x+3).
</pre>

Solved.