Precalculus : Find the Vertex and the Axis of Symmetry of a Parabola

Study concepts, example questions & explanations for Precalculus

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Example Questions

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Example Question #1 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the axis of symmetry and vertex of the following parabola:

Possible Answers:

Correct answer:

Explanation:

The first step of the problem is to find the axis of symmetry using the following formula:

Where a and b are determined from the format for the equation of a parabola:

We can see from the equation given in the problem that a=1 and b=-3, so we can plug these values into the formula to find the axis of symmetry of our parabola:

Keep in mind that the vertex of the parabola lies directly on the axis of symmetry. That is, the x-coordinate of the axis of symmetry will be the same as that of the vertex of the parabola. Now that we know the vertex is at the same x-coordinate as the axis of symmetry, we can simply plug this value into our function to find the y-coordinate of the vertex:

So the vertex occurs at the point:

Example Question #2 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the equation of the axis of symmetry: 

Possible Answers:

Correct answer:

Explanation:

Rewrite the equation in standard form .

The vertex formula is:

Determine the necessary coefficients.

Plug in these values to the vertex formula.

The axis of symmetry is .

 

Example Question #1 : Parabolas

Find the location of the vertex of the following parabola:

Possible Answers:

Correct answer:

Explanation:

The vertex can be thought of as the center of a parabola. Begin by finding the axis of symmetry with the following formula:

Where b and a come from the standard equation of a parabola:

So given our parabola

This gives us the x-coordinate of our vertex. find the y-coordinate by plugging in our x-coordinate.

So our vertex is:

Example Question #4 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the vertex of the parabola:  

Possible Answers:

Correct answer:

Explanation:

The polynomial is already in  format.

To find the vertex, use the following equation:

Substitute the coefficients and solve for the vertex.

The vertex is at .

Example Question #5 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the vertex and the equation of the axis of symmetry for .

Possible Answers:

Correct answer:

Explanation:

Rewrite  in standard parabolic form, .

Write the vertex formula and substitute the values.

The equation of the axis of symmetry is .

Substitute this value back into the original equation .

The vertex is at .

Example Question #6 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the axis of symmetry and the vertex of the parabola given by the following equation:

Possible Answers:

Vertex at 

Axis of symmetry at 

Vertex at 

Axis of symmetry at 

Vertex at 

Axis of symmetry at 

Vertex at 

Axis of symmetry at 

Correct answer:

Vertex at 

Axis of symmetry at 

Explanation:

Find the axis of symmetry and the vertex of the parabola given by the following equation:


To find the axis of symmetry of a parabola in standard form, , use the following equation:

So...

This means that we have an axis of symmetry at . Or, to put it more plainly, at  we could draw a vertical line which would perfectly cut our parabola in half!

So, we are halfway there, now we need the coordinates of our vertex. We already know the x-coordinate, which is 7. To find the y-coordinate, simply plug 7 into the parabola's formula and solve!

This makes our vertex the point 

Example Question #7 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the vertex of the parabola:

Possible Answers:

Correct answer:

Explanation:

The vertex form for a parabola is given below:

 

To complete the square, take the coefficient next to the x term, divide by  and raise the number to the second power. In this case, . Then take value and add it to add inside the parenthesis and subtract on the outside. 

Now factor and simplify:

Fromt the values of  and , the vertex is at 

Example Question #11 : Parabolas

Find the vertex of the parabola:

Possible Answers:

Correct answer:

Explanation:

The vertex form for a parabola is given below:

  

To complete the square, take the value next to the x term, divide by 2 and raise the number to the second power. In this case,. Then take value and add it to add inside the parenthesis and subtract on the outside. 

Now factor and simplify:

Fromt the values of h and k, the vertex is at 

Example Question #1 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the vertex of the parabola:

Possible Answers:

Correct answer:

Explanation:

The vertex form for a parabola is given below:

   

To complete the square, take the value next to the x term, divide by  and raise the number to the second power. In this case, . Then take value and add it to add inside the parenthesis and subtract on the outside. Remember to distribute before subtracting to the outside.

 

Now factor and simplify:

From the values of  and , the vertex is at 

Example Question #9 : Find The Vertex And The Axis Of Symmetry Of A Parabola

Find the vertex of the parabola:

Possible Answers:

Correct answer:

Explanation:

The vertex form for a parabola is given below:

Factor the equation and transform it into the vertex form.

 

To complete the square, take the value next to the x term, divide by  and raise the number to the second power. In this case, . Then take value and add it to add inside the parenthesis and subtract on the outside. 

 

Now factor and simplify:

From the values of  and , the vertex is at 

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