Math Problem Statement

Write a quadratic function in standard form whose graph is shown with intercepts at (-2, 0) and (6, 0), and a vertex at (4, -3).

Solution

The graph shows a quadratic function with intercepts at (2,0)(-2, 0) and (6,0)(6, 0), and the vertex is at (4,3)(4, -3). To write the quadratic function in standard form, f(x)=ax2+bx+cf(x) = ax^2 + bx + c, we can follow these steps:

Step 1: Identify the factored form of the quadratic.

Since the x-intercepts are x=2x = -2 and x=6x = 6, the function in factored form is: f(x)=a(x+2)(x6)f(x) = a(x + 2)(x - 6) where aa is a constant to be determined.

Step 2: Use the vertex to find aa.

We know the vertex is (4,3)(4, -3), so substitute x=4x = 4 and f(x)=3f(x) = -3 into the equation to solve for aa: 3=a(4+2)(46)-3 = a(4 + 2)(4 - 6) 3=a(6)(2)-3 = a(6)(-2) 3=12a-3 = -12a a=312=14a = \frac{-3}{-12} = \frac{1}{4}

Step 3: Write the equation in factored form.

Now that we know a=14a = \frac{1}{4}, the function in factored form is: f(x)=14(x+2)(x6)f(x) = \frac{1}{4}(x + 2)(x - 6)

Step 4: Expand to write in standard form.

To convert this into standard form, expand the factors: f(x)=14(x26x+2x12)f(x) = \frac{1}{4}(x^2 - 6x + 2x - 12) f(x)=14(x24x12)f(x) = \frac{1}{4}(x^2 - 4x - 12) f(x)=14x214(4x)14(12)f(x) = \frac{1}{4}x^2 - \frac{1}{4}(4x) - \frac{1}{4}(12) f(x)=14x2x3f(x) = \frac{1}{4}x^2 - x - 3

Thus, the quadratic function in standard form is: f(x)=14x2x3f(x) = \frac{1}{4}x^2 - x - 3

Would you like more details or have any further questions?

Here are 5 related questions to explore further:

  1. How do you convert a quadratic function from vertex form to standard form?
  2. What is the significance of the vertex in a quadratic function?
  3. How do you determine the direction in which a parabola opens?
  4. How can you find the axis of symmetry of a parabola?
  5. What methods can be used to find the roots of a quadratic equation?

Tip: Remember, the vertex form of a quadratic equation is particularly useful when you know the vertex, making it easier to graph.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factored Form
Vertex

Formulas

Factored form of quadratic equation: f(x) = a(x - r1)(x - r2)
Standard form of quadratic equation: f(x) = ax^2 + bx + c

Theorems

Quadratic formula
Vertex form to standard form conversion

Suitable Grade Level

Grades 9-10