# Identify the vertex of the quadratic function in standard form

How to Find Vertex of a Quadratic Function :. Here we are going to see some example problems to understand finding vertex of a quadratic function. To find the vertex form of the parabola, we use the concept completing the square method. Vertex form of a quadratic function :. In order to find the maximum or minimum value of quadratic function, we have to convert the given quadratic equation in the above form.

Question 1 :. Solution :. After having gone through the stuff given above, we hope that the students would have understood " How to Find Vertex of a Quadratic Function".

Apart from the stuff given in this section, if you need any other stuff in math, please use our google custom search here. You can also visit our following web pages on different stuff in math. Variables and constants. Writing and evaluating expressions.

Solving linear equations using elimination method. Solving linear equations using substitution method. Solving linear equations using cross multiplication method. Solving one step equations. Solving quadratic equations by factoring. Solving quadratic equations by quadratic formula.

Solving quadratic equations by completing square. Nature of the roots of a quadratic equations. Sum and product of the roots of a quadratic equations. Algebraic identities. Solving absolute value equations. Solving Absolute value inequalities. Graphing absolute value equations.Quadratic equations are mathematical functions where one of the x variables is squared, or taken to the second power like this: x 2. When these functions are graphed, they create a parabola which looks like a curved "U" shape on the graph.

This is why a quadratic equation is sometimes called a parabola equation. Two important values concerning these mathematical functions are the x-intercept and the y-intercept. The x-intercept indicates where the parabola graph of that function crosses the x axis. There can be one or two x intercepts for a single quadratic equations.

The y-intercept indicates where the parabola crosses the y axis. There is only one y intercept for each quadratic equation.

The y-intercept is where the parabola of a function crosses or intercepts the y axis. Another way to define the y-intercept is the value of y when x is equal to zero. For example, let's say your y value of the y intercept is 6.

You would write the y intercept as 0, 6. Quadratic equations come in three general forms. These are the standard form, vertex form and factored form. Each of the forms looks drastically different, but the method for finding the y intercept of a quadratic equation is the same despite the various forms. Standard form is perhaps the most common and the easiest to understand. Simply plug zero 0 in as the value of x in the standard quadratic equation and solve.

Here's an example. Assign "0" as your x value and solve. Lastly, you have factored form. Again, you simply plug "0" in as the value of x and solve.The standard form of a quadratic function is. Because h is the x-coordinate of the vertex, we can use this value to find the y-value, k, of the vertex. Example :. Solution :. Step 1 :. Step 2 :. Step 3 :. Substitute the value of h into the equation for x to find k, the y-coordinate of the vertex.

Substitute the value of h for x into the equation to find the y-coordinate of the vertex, k :. Axis of symmetry of a quadratic function can be determined by the x-coordinate of the vertex. Step 4 :. Step 5 :.

Find a point symmetric to the y-intercept across the axis of symmetry. Step 6 :. Once we have three points associated with the quadratic function, we can sketch the parabola based on our knowledge of its general shape. Find the maximum profit that the company can expect to earn. The x-axis shows the selling price and the y-axis shows the profit. The maximum y-value of the profit function occurs at the vertex of its parabola.

Find the vertex of the parabola. Use the function to find the x-coordinate and y-coordinate of the vertex. Find the equation of a parabola that passes through the points :. Write the three equations by substituting the given x and y-values into the standard form of a parabola equation. Substitute 1 for a, -3 for b, and for c in the standard form of quadratic equation. Confirm that the graph of the equation passes through the given three points.

Apart from the stuff given above, if you need any other stuff in math, please use our google custom search here. You can also visit our following web pages on different stuff in math. Variables and constants. Writing and evaluating expressions. Solving linear equations using elimination method. Solving linear equations using substitution method. Solving linear equations using cross multiplication method.The graph of a quadratic function is a curve called a parabola. Parabolas may open upward or downward and vary in "width" or "steepness", but they all have the same basic "U" shape.

The picture below shows three graphs, and they are all parabolas. All parabolas are symmetric with respect to a line called the axis of symmetry.

A parabola intersects its axis of symmetry at a point called the vertex of the parabola. You know that two points determine a line. This means that if you are given any two points in the plane, then there is one and only one line that contains both points. A similar statement can be made about points and quadratic functions. Given three points in the plane that have different first coordinates and do not lie on a line, there is exactly one quadratic function f whose graph contains all three points.

The applet below illustrates this fact. The graph contains three points and a parabola that goes through all three. The corresponding function is shown in the text box below the graph. If you drag any of the points, then the function and parabola are updated. See the section on manipulating graphs.

### Quadratic Functions in Standard Form

The functions in parts a and b of Exercise 1 are examples of quadratic functions in standard form. If a is positive, the graph opens upward, and if a is negative, then it opens downward.

Any quadratic function can be rewritten in standard form by completing the square. See the section on solving equations algebraically to review completing the square.

The steps that we use in this section for completing the square will look a little different, because our chief goal here is not solving an equation. Note that when a quadratic function is in standard form it is also easy to find its zeros by the square root principle.

Sketch the graph of f and find its zeros and vertex.

## How to Write Quadratic Equations in Vertex Form

Group the x 2 and x terms and then complete the square on these terms. When we were solving an equation we simply added 9 to both sides of the equation. In this setting we add and subtract 9 so that we do not change the function.

If the coefficient of x 2 is not 1, then we must factor this coefficient from the x 2 and x terms before proceeding. Sketch the graph of f ,find its vertex, and find the zeros of f. In some cases completing the square is not the easiest way to find the vertex of a parabola. If the graph of a quadratic function has two x-intercepts, then the line of symmetry is the vertical line through the midpoint of the x-intercepts. The x-intercepts of the graph above are at -5 and 3.

The line of symmetry goes through -1, which is the average of -5 and 3. A rancher has meters of fence to enclose a rectangular corral with another fence dividing it in the middle as in the diagram below.

As indicated in the diagram, the four horizontal sections of fence will each be x meters long and the three vertical sections will each be y meters long. There is not much we can do with the quantity A while it is expressed as a product of two variables. However, the fact that we have only meters of fence available leads to an equation that x and y must satisfy. We now have y expressed as a function of x, and we can substitute this expression for y in the formula for total area A.

We need to find the value of x that makes A as large as possible.

Find the axis of symmetry and your vertex

A is a quadratic function of x, and the graph opens downward, so the highest point on the graph of A is the vertex. Since A is factored, the easiest way to find the vertex is to find the x-intercepts and average.Converting an equation to vertex form can be tedious and require an extensive degree of algebraic background knowledge, including weighty topics such as factoring. In this form, the vertex is denoted by h, k. The vertex of a quadratic equation is the highest or lowest point on its graph, which is known as a parabola.

Ensure that your equation is written in standard form. Move the constant to the left side of the equals sign by adding or subtracting it. A constant is a number lacking an attached variable. Square this result. In the example, square 2, producing 4. Place this number, preceded by its sign, in the empty space. Add this to the constant on the left side of the equation. Factor the quadratic inside the parentheses, which is a perfect square.

Move the constant on the left-hand side of the equation back over to the right by adding or subtracting it. The equation is now in vertex form. Harris holds a Bachelor of Science in Mathematics from Penn State University; she taught high school math for several years and has also worked in the field of instructional design. About the Author. Photo Credits. Copyright Leaf Group Ltd.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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