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put this solution on YOUR website!the vertex form of a parabolic (quadratic) equation is y-k=a(x-h)^2
__ vertex is (h,k) and a is a measure of the width of the opening of the parabola
using the vertex __ y-11=a(x-4)^2
substituting the y-intercept __ 3-11=a(0-4)^2 __ -8=a(16) __ -1/2=a
y-11=(-1/2)(x-4)^2