Vertex form of the parabola is y = a*(x-3)^2 + 5. To find the unknown coefficient "a", use the fact that the given point (5,-3) belongs to the parabola -3 = a*(5-3)^2 + 5. It gives -3 - 5 = a*2^2 -8 = 4a a == -2. Thus the parabola is y = -2(x-3)^2 + 5. ANSWER