Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
Chapter Review
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Exercise 10 Page 85

Start by identifying p, h, and k.

Focus: (0,9)
Directrix: y=- 9
Axis of Symmetry: x=0

Practice makes perfect

Before we begin, note that in the given equation the variable that is raised to the second power is x. 36y=x^2 Therefore, the axis of symmetry of the parabola is a vertical line.

Finding the Desired Information

Let's recall the general form of the equation for this type of parabola. y= 1/4 * p(x- h)^2+ k In order to match this form perfectly, let's rewrite our equation. 36y=x^2 ⇔ y= 1/36x^2 We need to identify the values of p, h, and k. Let's start with p. To do so, we will solve the equation 14 p=136. We set it equal to 136, because it is the coefficient of the parenthetical factor.

1/4p=1/36
Solve for p
1=4p/36
1=p/9
9=p
p=9

Knowing that p= 9, we can rewrite the equation. y= 1/36x^2 ⇕ y= 1/4 * 9(x- 0)^2+ 0 Now we can see that p= 9, h= 0, and k= 0. By recalling the corresponding formulas we can find the focus, directrix, and axis of symmetry of the parabola.

Focus Directrix Axis of Symmetry
Formula ( h, k+ p) y= k- p x= h
Value ( 0, 0+ 9) ⇒ (0,9) y= 0- 9 ⇒ y=- 9 x= 0

Drawing the Parabola

Now, let's draw the parabola using the obtained information.