Big Ideas Math Algebra 2, 2014
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Big Ideas Math Algebra 2, 2014 View details
7. Modeling with Exponential and Logarithmic Functions
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Exercise 45 Page 348

Which variable is raised to the second power? Does it mean that the axis of symmetry of the parabola is a horizontal or a vertical line?

Focus: (0, 116)
Directrix: y=- 116
Axis of Symmetry: x=0
Graph:

Practice makes perfect

Before we begin, note that in the given equation the variable that is raised to the second power is x. y=4x^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 We need to identify the values of k, h, and p. Let's start with p. To do so, we will solve the equation 14 p=4. We set it equal to 4 because this is the coefficient of the x^2 term.
1/4p=4
â–Ľ
Solve for p
1/4p(1/4)=1
1/16p=1
1/16=p
p=1/16
Knowing that p= 116, we can rewrite the equation. y=4x^2 ⇕ y=1/4( 1/16)(x- 0)^2+ 0 Now we have that k= 0, h= 0, and p= 116. 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+ 1/16)
⇓
(0,1/16)
y= 0- 1/16
⇓
y=- 1/16
x= 0

Drawing the Parabola

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