Axis of Symmetry

Definition

The axis of symmetry is a line that divides a symmetric figure, such as a parabola, into two equal halves. It represents the midpoint or center of the symmetric figure, where the function changes direction from increasing to decreasing or vice versa.

5 Must Know Facts For Your Next Test

1. The axis of symmetry is important in solving quadratic equations using the square root property, completing the square, and the quadratic formula.
2. The axis of symmetry is also crucial in graphing quadratic functions, as it helps determine the vertex and the direction of the parabola.
3. The equation of the axis of symmetry is given by $x = -b/2a$, where $a$ and $b$ are the coefficients of the quadratic function $f(x) = ax^2 + bx + c$.
4. The axis of symmetry is perpendicular to the $x$-axis and passes through the vertex of the parabola.
5. The $y$-coordinate of the vertex, which lies on the axis of symmetry, can be found by substituting the $x$-coordinate of the axis of symmetry into the original quadratic function.

Review Questions

• Explain how the axis of symmetry is used to solve quadratic equations using the square root property.
  • When solving quadratic equations using the square root property, the axis of symmetry is important because it represents the midpoint of the parabolic graph. By finding the $x$-coordinate of the axis of symmetry, which is given by $x = -b/2a$, we can then use this value to determine the two solutions to the quadratic equation. The square root property states that the solutions are $x = (-b ext{ extpm } ext{ extsqrt{b^2 - 4ac}}) / 2a$, where $a$, $b$, and $c$ are the coefficients of the quadratic equation.
• Describe the role of the axis of symmetry in graphing quadratic functions using their properties.
  • When graphing quadratic functions using their properties, the axis of symmetry is a crucial element. The axis of symmetry passes through the vertex of the parabola and divides the graph into two equal halves. By finding the $x$-coordinate of the axis of symmetry, which is given by $x = -b/2a$, we can then determine the $y$-coordinate of the vertex by substituting this value into the original quadratic function. This information about the vertex and the axis of symmetry allows us to sketch the parabolic graph accurately.
• Analyze how the axis of symmetry relates to the graph of a parabola and the solutions to a quadratic equation.
  • The axis of symmetry of a parabola is closely connected to both the graph of the parabola and the solutions to the corresponding quadratic equation. The axis of symmetry represents the line of reflection, where the parabolic graph is divided into two equal halves. This means that the solutions to the quadratic equation, which are the $x$-intercepts of the parabola, are equidistant from the axis of symmetry. Additionally, the vertex of the parabola, which is the point where the function changes direction, lies on the axis of symmetry. By understanding the relationship between the axis of symmetry, the graph of the parabola, and the solutions to the quadratic equation, you can effectively solve, graph, and analyze quadratic functions.

Related terms

Parabola:

A parabola is a U-shaped curve that is the graph of a quadratic function. It has an axis of symmetry that passes through the vertex of the parabola.

Vertex:

The vertex of a parabola is the point where the parabola changes direction from increasing to decreasing or vice versa. It lies on the axis of symmetry.

Quadratic Function:

A quadratic function is a polynomial function of the form $f(x) = ax^2 + bx + c$, where $a$, $b$, and $c$ are real numbers. Quadratic functions have a parabolic graph with an axis of symmetry.