Math Problem Statement

how do you put f (x) = 2x^2 - 6x +7 into vertex form

Solution

To convert the quadratic function f(x)=2x26x+7f(x) = 2x^2 - 6x + 7 into vertex form, we follow the method of completing the square. The vertex form of a quadratic function is given by:

f(x)=a(xh)2+kf(x) = a(x-h)^2 + k

where (h,k)(h, k) is the vertex of the parabola.

Steps:

  1. Factor out the coefficient of x2x^2 from the first two terms: f(x)=2(x23x)+7f(x) = 2(x^2 - 3x) + 7

  2. Complete the square inside the parentheses:

    • Take the coefficient of xx (which is 3-3), divide it by 2, and square it: (32)2=94\left(\frac{-3}{2}\right)^2 = \frac{9}{4}
    • Add and subtract this value inside the parentheses: f(x)=2(x23x+9494)+7f(x) = 2\left(x^2 - 3x + \frac{9}{4} - \frac{9}{4}\right) + 7
    • Group the perfect square trinomial: f(x)=2((x32)294)+7f(x) = 2\left(\left(x - \frac{3}{2}\right)^2 - \frac{9}{4}\right) + 7
  3. Simplify the equation:

    • Distribute the 2: f(x)=2(x32)22×94+7f(x) = 2\left(x - \frac{3}{2}\right)^2 - 2 \times \frac{9}{4} + 7 f(x)=2(x32)292+7f(x) = 2\left(x - \frac{3}{2}\right)^2 - \frac{9}{2} + 7

    • Combine constants: f(x)=2(x32)2+52f(x) = 2\left(x - \frac{3}{2}\right)^2 + \frac{5}{2}

Final Answer:

The vertex form of the quadratic function is:

f(x)=2(x32)2+52f(x) = 2\left(x - \frac{3}{2}\right)^2 + \frac{5}{2}

In this form, the vertex is (32,52)\left(\frac{3}{2}, \frac{5}{2}\right).

Would you like a more detailed explanation of any step?


Here are 5 related questions to explore further:

  1. How can you find the vertex directly from the standard form?
  2. What is the significance of the vertex in a quadratic function?
  3. How does completing the square help in solving quadratic equations?
  4. How do transformations affect the graph of a quadratic function?
  5. How can the quadratic formula be used to find the roots of f(x)f(x)?

Tip: The hh-value in the vertex form (xh)2(x-h)^2 shifts the parabola horizontally, while kk shifts it vertically!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vertex Form
Completing the Square

Formulas

Vertex form: f(x) = a(x-h)^2 + k
Standard form: f(x) = ax^2 + bx + c
Formula for completing the square: (b/2)^2

Theorems

Vertex Form Theorem
Completing the Square Method

Suitable Grade Level

Grades 9-12