Math Problem Statement

y=2(x+3)(x-1) Opens Up or down? is the vertex a Max or Min? X-intercepts Axis of symmetry is x = vertex Domain and range. and help me find out what is up and down and min or max

Solution

We are analyzing the quadratic function y=2(x+3)(x1)y = 2(x+3)(x-1). Here's how to approach each question:


Step 1: Determine if the parabola opens up or down

The parabola opens up if the coefficient of x2x^2 is positive, and opens down if it is negative.

  1. Rewrite the equation into standard form by expanding: y=2(x+3)(x1)y = 2(x+3)(x-1) Expand: y=2(x2+2x3)y = 2(x^2 + 2x - 3) Simplify: y=2x2+4x6y = 2x^2 + 4x - 6 The coefficient of x2x^2 is 22, which is positive. Therefore, the parabola opens up.

Step 2: Is the vertex a maximum or minimum?

  • Since the parabola opens up, the vertex is the lowest point. The vertex represents a minimum value.

Step 3: Find the vertex

To find the vertex, we use the formula for the xx-coordinate of the vertex: x=b2ax = -\frac{b}{2a} From y=2x2+4x6y = 2x^2 + 4x - 6:

  • a=2a = 2, b=4b = 4, c=6c = -6 x=42(2)=44=1x = -\frac{4}{2(2)} = -\frac{4}{4} = -1

To find the yy-coordinate of the vertex, substitute x=1x = -1 into the equation: y=2(1)2+4(1)6y = 2(-1)^2 + 4(-1) - 6 y=2(1)46=246=8y = 2(1) - 4 - 6 = 2 - 4 - 6 = -8 The vertex is (1,8)(-1, -8).


Step 4: Find the x-intercepts

The x-intercepts occur when y=0y = 0. Using the factored form y=2(x+3)(x1)y = 2(x+3)(x-1), set y=0y = 0: 2(x+3)(x1)=02(x+3)(x-1) = 0 x+3=0orx1=0x+3 = 0 \quad \text{or} \quad x-1 = 0 x=3andx=1x = -3 \quad \text{and} \quad x = 1 The x-intercepts are (3,0)(-3, 0) and (1,0)(1, 0).


Step 5: Find the axis of symmetry

The axis of symmetry is the vertical line passing through the xx-coordinate of the vertex: Axis of symmetry: x=1\text{Axis of symmetry: } x = -1


Step 6: Domain and range

  1. Domain: Since this is a quadratic function, the domain is all real numbers: Domain: (,)\text{Domain: } (-\infty, \infty)
  2. Range: Since the parabola opens up and the vertex is the minimum point at y=8y = -8, the range is: Range: [8,)\text{Range: } [-8, \infty)

Summary of Results:

  1. Opens up (since a>0a > 0).
  2. Vertex is (1,8)(-1, -8).
  3. Vertex is a minimum.
  4. X-intercepts: (3,0)(-3, 0) and (1,0)(1, 0).
  5. Axis of symmetry: x=1x = -1.
  6. Domain: (,)(-\infty, \infty).
  7. Range: [8,)[-8, \infty).

Additional Notes:

To determine "up" or "down" and "min" or "max":

  • Look at the coefficient of x2x^2: if positive, the parabola opens up (minimum). If negative, it opens down (maximum).

Do you have any questions or need further details? Here are related questions:

  1. How do we find the vertex if the equation is not in standard form?
  2. Can we graph this function to visualize the results?
  3. How is the range determined based on the vertex?
  4. How do we find x-intercepts for functions not in factored form?
  5. How does the axis of symmetry relate to the vertex?

Tip: To check your work, graph the function and confirm the vertex, intercepts, and symmetry visually.

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Parabolas
Vertex Form
Factored Form
Axis of Symmetry
Domain and Range

Formulas

y = ax^2 + bx + c
x = -b/(2a)
y = a(x-h)^2 + k for vertex form

Theorems

Properties of Parabolas
Relationship between Coefficients and the Shape of the Parabola

Suitable Grade Level

Grades 8-10