Find the vertex, focus and directrix

Complex numbers, rational functions, logarithms, sequences and series, matrix operations, etc.
Posts: 6
Joined: Tue May 04, 2010 11:51 pm

Find the vertex, focus and directrix

Postby rowdy3 » Sat May 08, 2010 12:04 am

Sketech the graph of the equation y^2+4y+2x+10=0. Identify the vertex, the focus and the equation for the directrix. Use the completing the square to put the equation into standard form as your first step.

This is what I did.

y^2 + 4y = -2x-10

y^2 + 4y + 4 = -2x-6

(y+2)^2= -2(x+3)

vertex: (-3, -2)

Focus: (-3.5, -2)

Directrix: -2.5

User avatar
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm

Postby stapel_eliz » Sat May 08, 2010 1:40 pm

Looks good to me! :wink:

Return to “Advanced Algebra ("pre-calculus")”