Question 83166
The general expression for a quadratic in completed square form is:
where the vertex would be (-b,c).
1) Since the vertex is (-8,4), then the formula should be:
And to find the value of a, substitute the other point (-6,-2) in the equation:
giving the value of a as {{{-3/2=-1.5}}}

2) To change a normal quadratic into the completed square form, first take half the coefficient of x (2) and place it in a bracket like this:
Now this expression gives you {{{x^2+4x+4}}} and since we only need the first two terms, we need to eliminate the last one. To do that you simply subtract 4:
And finally place the last term right after that.
{{{(x+2)^2-4-1=(x+2)^2-5}}} This means the vertex is (-2,-5)

3) Same as the first one, and to make a quadratic function "open down" you will need to put a negative sign before the bracket: