Math Problem Statement

Find range of f(x)=4x^2 +4x+3

Solution

To find the range of the quadratic function f(x)=4x2+4x+3f(x) = 4x^2 + 4x + 3, we can first rewrite it in vertex form by completing the square.

  1. Identify the coefficients:

    • a=4a = 4
    • b=4b = 4
    • c=3c = 3
  2. Complete the square: f(x)=4(x2+x)+3f(x) = 4(x^2 + x) + 3 Take half of the coefficient of xx (which is 11), square it ((12)2=14\left(\frac{1}{2}\right)^2 = \frac{1}{4}), and add and subtract this inside the parentheses: f(x)=4(x2+x+1414)+3f(x) = 4\left(x^2 + x + \frac{1}{4} - \frac{1}{4}\right) + 3 Simplifying gives: f(x)=4((x+12)214)+3f(x) = 4\left(\left(x + \frac{1}{2}\right)^2 - \frac{1}{4}\right) + 3 f(x)=4(x+12)21+3f(x) = 4\left(x + \frac{1}{2}\right)^2 - 1 + 3 f(x)=4(x+12)2+2f(x) = 4\left(x + \frac{1}{2}\right)^2 + 2

  3. Determine the vertex: The vertex form f(x)=4(x+12)2+2f(x) = 4\left(x + \frac{1}{2}\right)^2 + 2 shows that the vertex is at (12,2)\left(-\frac{1}{2}, 2\right).

  4. Analyze the parabola: Since a=4>0a = 4 > 0, the parabola opens upwards. The minimum value of f(x)f(x) occurs at the vertex.

  5. Find the range: The minimum value is 22, and since the parabola opens upwards, the range is: [2,)[2, \infty)

Conclusion

The range of the function f(x)=4x2+4x+3f(x) = 4x^2 + 4x + 3 is [2,)[2, \infty).

Do you want any details or have any questions? Here are some related questions you might consider:

  1. How would you find the vertex of a different quadratic function?
  2. What is the significance of the discriminant in a quadratic equation?
  3. How do you determine if a quadratic function opens upward or downward?
  4. Can you explain how to graph a quadratic function?
  5. What are some applications of quadratic functions in real life?

Tip: When completing the square, always remember to balance the equation by adding and subtracting the same value to maintain equality.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Functions
Vertex Form

Formulas

f(x) = a(x-h)^2 + k
Completing the square

Theorems

Vertex theorem for quadratic functions

Suitable Grade Level

Grades 8-10