Question 757598
The quadratic function can be written as

{{{y = a(x-h)^2+k}}}

where (h,k) is the given vertex, and a is the coefficient of the squared term. Thus you can write:

{{{y=a(x+3)^2-1}}}

If you expand:

{{{y=a*x^2 + 6a*x+9a-1}}}

Replace the y with 0 and x with 4:

{{{0 = 16a + 24a + 9a -1}}}

Solve for a:

{{{0= 49a -1}}}

{{{1=49a}}}

{{{1/49=a}}}