You memorize the general vertex form

y = a(x-h)²+k

You compare your equation to that:

a=-1, h=2, k=7

The vertex is the point (h,k) = (2,7)

You plot that point:



Now from that vertex, go right and left 1 unit and then "a" units.
When a is positive you go up, and when it's negative you go down.
So we go right and left 1 unit from the vertex and down 1 unit from
each because "a" is -1.




Then we sketch in the graph:



Edwin