Vertex of the Parabola

The vertex of the parabola indicates the highest or maximum point of a sad-faced parabola, and the lowest or minimum point of a happy-faced parabola.

The first method to find the vertex of the parabola: (with formula)

First step: We will find the XX of the vertex according to the formula x=(b)2ax=\frac{(-b)}{2a}

Second step: We will place the XX of the vertex we have found into the original parabola equation to find the YY of the vertex.


Second method to find the vertex of the parabola: according to 2 points of intersection with the X-axis and use of symmetry

First step: Find two points of intersection of the parabola with the XX axis using the quadratic formula.

Second step: Find the XX of the vertex: the point that is exactly between two points of intersection. The calculation will be done through the average of two XXs of the intersection points.

Third step: Place the XX of the vertex we have found into the original parabola equation to solve for the YY of the vertex.

Suggested Topics to Practice in Advance

  1. The quadratic function
  2. Parabola
  3. Plotting the Quadratic Function Using Parameters a, b and c
  4. Finding the Zeros of a Parabola
  5. Positive and Negative intervals of a Quadratic Function
  6. Increasing and Decreasing Intervals of a Parabola

Practice The Vertex of the Parabola

Examples with solutions for The Vertex of the Parabola

Exercise #1

The following function has been plotted on the graph below:

f(x)=x28x+16 f(x)=x^2-8x+16

Calculate point C.

CCC

Video Solution

Step-by-Step Solution

To solve the exercise, first note that point C lies on the X-axis.

Therefore, to find it, we need to understand what is the X value when Y equals 0.

 

Let's set the equation equal to 0:

0=x²-8x+16

We'll use the preferred method (trinomial or quadratic formula) to find the X values, and we'll discover that

X=4

 

Answer

(4,0) (4,0)

Exercise #2

The following function has been graphed below:

f(x)=x26x f(x)=x^2-6x

Calculate point C.

CCCAAABBB

Video Solution

Step-by-Step Solution

To solve this problem, we'll calculate the vertex of the parabola given by the quadratic function f(x)=x26x f(x) = x^2 - 6x .

  • Step 1: Identify the coefficients a=1 a = 1 and b=6 b = -6 .
  • Step 2: Use the vertex formula x=b2a x = -\frac{b}{2a} to find the x-coordinate of the vertex.
  • Step 3: Substitute the calculated x-coordinate back into the function to find the y-coordinate.

Now, let's compute:

Step 1: The function is f(x)=x26x f(x) = x^2 - 6x with coefficients a=1 a = 1 and b=6 b = -6 .

Step 2: Apply the vertex formula: x=62×1=62=3 x = -\frac{-6}{2 \times 1} = \frac{6}{2} = 3 .

Step 3: For x=3 x = 3 , substitute into f(x) f(x) to find the y-coordinate:

f(3)=(3)26×3=918=9 f(3) = (3)^2 - 6 \times 3 = 9 - 18 = -9 .

Therefore, the coordinates of the point C, which is the vertex, are (3,9)(3, -9).

The correct answer is (3,9)(3, -9), which corresponds to the given correct choice.

Answer

(3,9) (3,-9)

Exercise #3

The following function has been graphed below.

f(x)=x26x+8 f(x)=x^2-6x+8

Calculate point B.

BBB

Video Solution

Step-by-Step Solution

To calculate point B, we should determine the vertex of the quadratic function f(x)=x26x+8 f(x) = x^2 - 6x + 8 .

The x-coordinate of the vertex can be found using the formula x=b2a x = -\frac{b}{2a} .

In our equation, we have a=1 a = 1 and b=6 b = -6 , therefore:

x=62×1=62=3 x = -\frac{-6}{2 \times 1} = \frac{6}{2} = 3

Next, we substitute x=3 x = 3 back into the function to find the y-coordinate:

f(3)=326×3+8=918+8=1 f(3) = 3^2 - 6 \times 3 + 8 = 9 - 18 + 8 = -1

Thus, the vertex, which is point B, is (3,1) (3, -1) .

Therefore, the solution indicates that point B is at (3,1) (3, -1) .

Answer

(3,1) (3,-1)

Exercise #4

The following function has been graphed below:

f(x)=x2+5x+6 f(x)=-x^2+5x+6

Calculate point C.

BBBAAACCC

Video Solution

Step-by-Step Solution

To answer the question, we must first remember the formula for finding the vertex of a parabola:

Now let's substitute the known data into the formula:

-5/2(-1)=-5/-2=2.5

In other words, the x-coordinate of the vertex of the parabola is found when the X value equals 2.5.

Now let's substitute this into the parabola equation to find the Y value:

-(2.5)²+5*2.5+6= 12.25

Therefore, the coordinates of the vertex of the parabola are (2.5, 12.25).

Answer

(212,1214) (2\frac{1}{2},12\frac{1}{4})

Exercise #5

Find the vertex of the parabola

y=(x+1)2 y=(x+1)^2

Video Solution

Step-by-Step Solution

The equation y=(x+1)2 y = (x+1)^2 is already in the vertex form y=(xh)2+k y = (x-h)^2 + k , where (h,k)(h, k) is the vertex of the parabola.

By comparing, we have:

  • The expression inside the square is (x+1) (x+1) , which can be rewritten as (x(1)) (x - (-1)) . Thus, h=1 h = -1 .
  • The term k k is not present, which means k=0 k = 0 .

Therefore, the vertex (h,k)(h, k) of the parabola is (1,0)(-1, 0).

Thus, the correct answer is (1,0)(-1, 0).

Answer

(1,0) (-1,0)

Exercise #6

Find the vertex of the parabola

y=(x1)21 y=(x-1)^2-1

Video Solution

Step-by-Step Solution

The given equation is y=(x1)21 y = (x-1)^2 - 1 . This equation is in the vertex form, y=a(xh)2+k y = a(x-h)^2 + k , where a a , h h , and k k are constants.

In this case, the given equation can be written as y=1(x1)2+(1) y = 1 \cdot (x-1)^2 + (-1) , indicating that a=1 a = 1 , h=1 h = 1 , and k=1 k = -1 .

The vertex form of the quadratic equation allows us to directly identify the vertex of the parabola as (h,k) (h, k) .

From our identification, it is clear that the vertex (h,k) (h, k) of the parabola is (1,1) (1, -1) .

Therefore, the vertex of the given parabola is (1,1) (1, -1) .

Answer

(1,1) (1,-1)

Exercise #7

Find the vertex of the parabola

y=(x3)21 y=(x-3)^2-1

Video Solution

Step-by-Step Solution

To solve for the vertex of the parabola given by the equation y=(x3)21 y = (x-3)^2 - 1 , we start by comparing the equation with the standard vertex form of a quadratic function: y=a(xh)2+k y = a(x-h)^2 + k .

In the given equation, y=(x3)21 y = (x-3)^2 - 1 , we identify:
- h=3 h = 3 , which corresponds to the horizontal shift of the parabola.
- k=1 k = -1 , which represents the vertical shift.

Therefore, the vertex of the parabola is at the point (h,k)(h, k), which is (3,1)(3, -1).

Thus, the vertex of the parabola is (3,1)(3, -1).

Answer

(3,1) (3,-1)

Exercise #8

Find the vertex of the parabola

y=x2+3 y=x^2+3

Video Solution

Step-by-Step Solution

To solve for the vertex of the parabola given by the equation y=x2+3 y = x^2 + 3 , we will follow these steps:

  • Step 1: Identify the coefficients from the equation. We have a=1 a = 1 , b=0 b = 0 , and c=3 c = 3 .
  • Step 2: Calculate the x-coordinate of the vertex using the formula x=b2a x = -\frac{b}{2a} . Since b=0 b = 0 , the formula becomes x=02×1=0 x = -\frac{0}{2 \times 1} = 0 .
  • Step 3: Find the y-coordinate of the vertex by substituting x=0 x = 0 back into the equation. Calculate y=(0)2+3=3 y = (0)^2 + 3 = 3 .

Therefore, the vertex of the parabola is at the point (0,3) (0, 3) .

This corresponds to choice 3: (0,3) (0,3) .

Answer

(0,3) (0,3)

Exercise #9

Find the vertex of the parabola

y=x2 y=x^2

Video Solution

Step-by-Step Solution

To find the vertex of the parabola y=x2 y = x^2 , we follow these steps:

  • Step 1: Identify the coefficients from the equation y=x2 y = x^2 . Here, a=1 a = 1 , b=0 b = 0 , and c=0 c = 0 .
  • Step 2: Use the vertex formula x=b2a x = -\frac{b}{2a} to find the x-coordinate of the vertex. Substituting the values, we get:
x=02×1=0 x = -\frac{0}{2 \times 1} = 0

Therefore, the x-coordinate of the vertex is 0 0 .

Step 3: Substitute x=0 x = 0 back into the equation to find the y-coordinate:

y=(0)2=0 y = (0)^2 = 0

Thus, the y-coordinate of the vertex is also 0 0 .

Therefore, the vertex of the parabola y=x2 y = x^2 is (0,0)(0,0).

The correct answer choice is: (0,0) (0,0) .

Answer

(0,0) (0,0)

Exercise #10

Find the vertex of the parabola

y=x26 y=x^2-6

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given information.
  • Step 2: Apply the vertex formula to find h h and k k .
  • Step 3: Determine the coordinates of the vertex.

Now, let's work through each step:
Step 1: The given quadratic equation is y=x26 y = x^2 - 6 where a=1 a = 1 , b=0 b = 0 , and c=6 c = -6 .
Step 2: We use the vertex formula:

h=b2a h = -\frac{b}{2a}
Substituting the values, h=021=0 h = -\frac{0}{2 \cdot 1} = 0 .

k=cb24a k = c - \frac{b^2}{4a}
Using the given values, k=60241=6 k = -6 - \frac{0^2}{4 \cdot 1} = -6 .

Step 3: Therefore, the vertex of the parabola is at (h,k)=(0,6) (h, k) = (0, -6) .

The solution to the problem is (0,6) (0, -6) .

Answer

(0,6) (0,-6)

Exercise #11

Find the vertex of the parabola

y=(x+1)21 y=(x+1)^2-1

Video Solution

Step-by-Step Solution

The given equation of the parabola is y=(x+1)21 y = (x+1)^2 - 1 .

This equation is already in the vertex form, y=a(xh)2+k y = a(x-h)^2 + k , where (h,k)(h, k) is the vertex.

By comparing, we identify:
The expression (x+1)(x + 1) implies that h=1h = -1 (since x+1x + 1 is equivalent to (x(1))(x - (-1))).
The constant 1-1 is the kk value.

Thus, the vertex (h,k)(h, k) is (1,1)(-1, -1).

Therefore, the vertex of the parabola is at the point (1,1)(-1,-1).

Answer

(1,1) (-1,-1)

Exercise #12

Find the vertex of the parabola

y=(x3)2 y=(x-3)^2

Video Solution

Step-by-Step Solution

To solve this problem, let's identify the vertex of the given parabola in the form y=(x3)2 y = (x - 3)^2 .

The parabola is already given in the vertex form of y=(xh)2+k y = (x - h)^2 + k , which is a special case of the quadratic equation where the vertex (h,kh, k) can be read directly from the equation.

  • Step 1: We compare the given equation y=(x3)2 y = (x - 3)^2 with the standard vertex form y=(xh)2+k y = (x - h)^2 + k .
  • Step 2: Notice that h=3 h = 3 and since there is no additional term added or subtracted outside the squared term, k=0 k = 0 .

Therefore, the vertex of the quadratic function y=(x3)2 y = (x - 3)^2 is (3,0) (3, 0) .

The correct choice from the multiple-choice options provided is the one that matches (3,0) (3, 0) .

The solution to the problem is the vertex (3,0) (3, 0) .

Answer

(3,0) (3,0)

Exercise #13

Find the vertex of the parabola

y=(x3)2+6 y=(x-3)^2+6

Video Solution

Step-by-Step Solution

To solve the problem of finding the vertex of the parabola y=(x3)2+6 y = (x-3)^2 + 6 , we take the following steps:

Step 1: Identify the form of the given equation.
The equation is given in the vertex form of a quadratic function, which is generally expressed as y=(xh)2+k y = (x-h)^2 + k .

Step 2: Recognize the coefficients.
In the given equation y=(x3)2+6 y = (x-3)^2 + 6 , compare it with the standard form y=(xh)2+k y=(x-h)^2 + k to identify h h and k k . Here, h=3 h = 3 and k=6 k = 6 .

Step 3: Determine the vertex.
The vertex of the parabola, therefore, is directly given by the point (h,k)=(3,6) (h, k) = (3, 6) .

As a conclusion, the vertex of the parabola described by the equation y=(x3)2+6 y = (x-3)^2 + 6 is located at the point (3,6) (3, 6) .

Answer

(3,6) (3,6)

Exercise #14

Find the vertex of the parabola

y=(x7)7 y=(x-7)-7

Video Solution

Step-by-Step Solution

The given equation is y=(x7)7 y = (x-7) - 7 .

First, simplify the equation:
y=x77=x14 y = x - 7 - 7 = x - 14 .

This is a linear equation in the form y=x14 y = x - 14 . However, since the problem asks about a vertex, there might be a reconsideration needed if a quadratic term is missing. Since the question specifies a parabola, let's convert back:

Let's convert this into a complete square form:

Express y=(x7)27 y = (x - 7)^2 - 7 , assuming we meant to represent:
y=(xh)2+k y = (x-h)^2 + k

The vertex form representation would look like:
y=(x7)2+(7) y = (x-7)^2 + (-7)

Hence, the vertex is (7,7)(7, -7).

Therefore, the vertex of the parabola is (7,7)(7, -7).

Answer

(7,7) (7,-7)

Exercise #15

Find the vertex of the parabola

y=(x+8)29 y=(x+8)^2-9

Video Solution

Step-by-Step Solution

To solve for the vertex of the parabola, we need to recognize that the equation y=(x+8)29 y = (x+8)^2 - 9 is already in vertex form, which is y=(xh)2+k y = (x-h)^2 + k .

Let's break down the given equation:

  • Rewrite the given equation: y=(x+8)29 y = (x+8)^2 - 9 .
    This matches the vertex form y=(xh)2+k y = (x - h)^2 + k .
  • Identify values: Here, h=8 h = -8 and k=9 k = -9 .

Thus, the vertex is located at the point (8,9)(-8, -9).

Comparing with the multiple-choice options provided:

  • Choice 1: (8,9)(-8, 9) - Incorrect k k.
  • Choice 2: (8,9)(8, -9) - Incorrect h h.
  • Choice 3: (8,9)(8, 9) - Incorrect both h h and k k.
  • Choice 4: (8,9)(-8, -9) - Correct.

Therefore, the vertex of the parabola is (8,9)(-8, -9).

Answer

(8,9) (-8,-9)

Topics learned in later sections

  1. Symmetry in a parabola