SOLUTION: Find the vertex, focus, and directrix of the parabola. Graph the equation. y^2 - 2y = 8x - 1

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Find the vertex, focus, and directrix of the parabola. Graph the equation. y^2 - 2y = 8x - 1      Log On


   



Question 854644: Find the vertex, focus, and directrix of the parabola. Graph the equation.
y^2 - 2y = 8x - 1

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Find the vertex, focus, and directrix of the parabola. Graph the equation.
y^2 - 2y = 8x - 1
complete the square:
(y^2-2y+1) = 8x - 1+1
(y-1)^2=8x
This is an equation of a parabola that opens right.
Its basic form of equation: (y-k)^2=4p(x-h)^2, (h,k)=coordinates of the vertex
For given parabola:
vertex: (0,1)
axis of symmetry: y=1
4p=8
p=2
focus: (2,1) (p-distance to the right of vertex on the axis of symmetry)
directrix: x=-2 (p-distance to the left of vertex on the axis of symmetry)
see graph below:
y=(8x)^.5+1
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C%288x%29%5E.5%2B1%2C-%288x%29%5E.5%2B1%29+