The general equation of a parabola is y-k=a(x-h)^2 where (h,k) is the origin and vertex. An upside-down parabola has negative a. If (h,k)=(1,2) and a=-1, y-2=-(x-1)^2 or y=2-(x-1)^2 or y=1+2x-x^2. To draw the parabola, first draw the vertical line x=1, because the parabola is symmetrical about this line. The vertex is the highest point on the graph and the line at (1,2). The parabola cuts the x axis when y=0, that is, when (x-1)^2=2, so x=1+sqrt(2)=2.41 and 1-sqrt(2)=-0.41 (approx) and it cuts the y axis at 1 when x=0. Label these intersects, so that whoever sees your graph will know you understand how to draw the graph, even if you're not good at drawing! The x intercepts are also the roots or zeroes of the equation 1+2x-x^2.