Math Problem Statement

How do you calculate the vertex of a function

Solution

To calculate the vertex of a quadratic function in the standard form:

f(x)=ax2+bx+cf(x) = ax^2 + bx + c

Steps:

  1. Find the x-coordinate of the vertex using the formula:

    xvertex=b2ax_{\text{vertex}} = \frac{-b}{2a}

  2. Find the y-coordinate of the vertex by substituting the x-coordinate back into the original quadratic function:

    yvertex=f(b2a)=a(b2a)2+b(b2a)+cy_{\text{vertex}} = f\left(\frac{-b}{2a}\right) = a\left(\frac{-b}{2a}\right)^2 + b\left(\frac{-b}{2a}\right) + c

Thus, the vertex (xvertex,yvertex)(x_{\text{vertex}}, y_{\text{vertex}}) is the point:

(b2a,f(b2a))\left( \frac{-b}{2a}, f\left(\frac{-b}{2a}\right) \right)

Alternatively, if the quadratic is given in vertex form:

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

The vertex is simply at (h,k)(h, k), where hh and kk are constants.

Example:

For the quadratic function:

f(x)=2x24x+1f(x) = 2x^2 - 4x + 1

  1. Find xvertexx_{\text{vertex}}:

    xvertex=(4)2(2)=44=1x_{\text{vertex}} = \frac{-(-4)}{2(2)} = \frac{4}{4} = 1

  2. Find yvertexy_{\text{vertex}} by substituting x=1x = 1 into f(x)f(x):

    yvertex=2(1)24(1)+1=24+1=1y_{\text{vertex}} = 2(1)^2 - 4(1) + 1 = 2 - 4 + 1 = -1

The vertex is (1,1)(1, -1).

Would you like more details or have any questions?

Related Questions:

  1. How do you convert a quadratic function to vertex form?
  2. What does the vertex of a parabola represent in real-world applications?
  3. How can you find the axis of symmetry of a quadratic function?
  4. How does the value of aa in the quadratic function affect the graph's shape?
  5. Can the vertex of a quadratic function be outside the visible part of the graph?

Tip:

The vertex gives the highest or lowest point on the graph, depending on whether the parabola opens upwards or downwards.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Vertex of a Parabola
Algebra

Formulas

x_{vertex} = -b / 2a
y_{vertex} = f(-b / 2a)
Vertex form: f(x) = a(x - h)^2 + k

Theorems

Quadratic Vertex Formula
Properties of Parabolas

Suitable Grade Level

Grades 9-11