Math Problem Statement

The graph represents a quadratic function. Write an equation of the function in standard form.

Solution

The graph provided represents a quadratic function, and we can derive its equation from key points. From the graph, the roots (x-intercepts) are x=2x = 2 and x=10x = 10, and the vertex is at (6,4)(6, -4).

The standard form of a quadratic function is:

y=ax2+bx+cy = ax^2 + bx + c

However, we will use the factored form first, based on the roots:

y=a(x2)(x10)y = a(x - 2)(x - 10)

Now, we need to determine the value of aa. Since the vertex is (6,4)(6, -4), we can substitute x=6x = 6 and y=4y = -4 into the equation:

4=a(62)(610)-4 = a(6 - 2)(6 - 10)

Simplifying:

4=a(4)(4)-4 = a(4)(-4)

4=16a-4 = -16a

Solving for aa:

a=416=14a = \frac{-4}{-16} = \frac{1}{4}

Thus, the equation of the quadratic function in factored form is:

y=14(x2)(x10)y = \frac{1}{4}(x - 2)(x - 10)

Now, expand this to write it in standard form:

y=14[(x2)(x10)]=14(x212x+20)y = \frac{1}{4}[(x - 2)(x - 10)] = \frac{1}{4}(x^2 - 12x + 20)

Distribute the 14\frac{1}{4}:

y=14x23x+5y = \frac{1}{4}x^2 - 3x + 5

Therefore, the equation of the quadratic function in standard form is:

y=14x23x+5y = \frac{1}{4}x^2 - 3x + 5

Would you like further details or have any questions? Here are five related questions you might explore:

  1. How can you find the vertex of a quadratic equation from its standard form?
  2. What is the significance of the value of aa in the quadratic equation?
  3. How would the graph change if aa was negative?
  4. How do you convert a quadratic equation from factored form to standard form?
  5. What methods can you use to find the roots of a quadratic equation?

Tip: Remember that the sign of aa determines the direction of the parabola—positive opens upwards, negative opens downwards!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Factoring
Vertex Form

Formulas

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

Theorems

Vertex Theorem
Root-Finding using Factored Form

Suitable Grade Level

Grades 9-11