Understanding equations and properties about conic sections

What is the focal width of the parabola?

y² = -28x

• 28

• -28

• 7

• -7

How can you tell whether a parabola opens up or opens down by looking at the equation?

• The vertex tells you the direction of the opening

• The value of "a" tells you the direction of the opening.

• All parabolas open upward

• All parabolas open downward

(y-4)² = -8(x+1)
What are the coordinates for the focus?

• (1,4)
• (-1,6)
• (-1,2)
• (-3,4)

If the vertex of a parabola is (2, −3), what is the axis of symmetry?

Find the equation of a parabola with vertex at (8, 21) and passes through point (12, -1).

• y = -¹¹/₈(x - 8)² + 21
• y = -¹¹/₂₀₀(x + 8)² + 21
• y = ¹¹/₈(x - 12)² - 1
• y = ¹¹/₂₀₀(x + 12)² - 1

The vertex is (0,–2) and the

focus is (0,0). What is the focal length?

• $-\frac{1}{8}x^2$

• -2

• $-\frac{1}{8}x^2-2$

•  $2$ 

Find the equation of a parabola with vertex at (-3, 4) and passes through point (-5, 6).

• y = ¹/₂(x + 3)² + 4
• y = ¹/₃₂(x - 3)² + 4
• y = -¹/₂(x + 5)² + 6
• y = -¹/₃₂(x - 5)² + 6

What's the vertex of this parabola?

• (0, 3)

• (-1, 0)

• (3, 0)

• (1, 4)

Since the parabola opens right, then the a-value had to be...

• positive

• negative

A parabola is upside-down when a is:

• negative
• positive
• 0
• infinite