Try this explanation:1. This curve is parabola; its equation is y=ax²+bx+c2. Using the formula for 'x' of vertex (x₀=-b/(2a)): x₀=-2/(2*1)=-1.3. If to substitute known x₀ into the equation of the given parabola it is possible to find y₀: y₀=x₀²+2x₀-15=1-2-15=-16.
answer: (-1;-16)