Find the vertex of the graph of the equation x - y^2 + 8y = 13.
Rearrange as
x -13 = y^2 - 8y complete the square on y
Take 1/2 of 8 = 4....square this and add to both sides
x -13 + 16 = y^2 - 8y + 16 factor the right side, simplify the left
x + 3 = ( y - 4)^2
x = (y - 4) ^2 - 3
The vertex is (-3, 4)
