Vertex form of the quadratic equation

The vertex form allows us to identify, very easily, the vertex of the parabola and hence its name.

The vertex form of the quadratic function is:
Y=a(Xp)2+cY=a(X-p)^2+c

Suggested Topics to Practice in Advance

  1. Standard Form of the Quadratic Function
  2. Factored form of the quadratic function

Practice Vertex Representation

Examples with solutions for Vertex Representation

Exercise #1

Find the standard representation of the following function:

f(x)=(x3)2+x f(x)=(x-3)^2+x

Video Solution

Step-by-Step Solution

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

  • Expand (x3)2(x-3)^2 using the formula for a square:
    (x3)2=x22×x×3+32=x26x+9(x-3)^2 = x^2 - 2 \times x \times 3 + 3^2 = x^2 - 6x + 9
  • Add the x x from f(x)=(x3)2+x f(x) = (x-3)^2 + x to the expanded terms:
    x26x+9+x x^2 - 6x + 9 + x
  • Combine like terms:
    x26x+x+9=x25x+9 x^2 - 6x + x + 9 = x^2 - 5x + 9

Therefore, the standard form of the function f(x) f(x) is f(x)=x25x+9 f(x) = x^2 - 5x + 9 .

Thus, the correct choice is Choice 3.

Answer

f(x)=x25x+9 f(x)=x^2-5x+9

Exercise #2

Find the standard representation of the following function

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

Video Solution

Step-by-Step Solution

To convert f(x)=(2x+1)21 f(x) = (2x+1)^2 - 1 into its standard quadratic form, we need to expand (2x+1)2 (2x+1)^2 first and then adjust for the subtraction of 1.

The expansion is carried out using the binomial expansion formula:

(2x+1)2=(2x)2+2(2x)(1)+12(2x + 1)^2 = (2x)^2 + 2(2x)(1) + 1^2.

Calculating each term gives:

  • (2x)2=4x2(2x)^2 = 4x^2
  • 2(2x)(1)=4x2(2x)(1) = 4x
  • 12=11^2 = 1

Combining these, we obtain:

(2x+1)2=4x2+4x+1(2x + 1)^2 = 4x^2 + 4x + 1

Now, substituting back into the original equation:

f(x)=(2x+1)21=(4x2+4x+1)1f(x) = (2x+1)^2 - 1 = (4x^2 + 4x + 1) - 1

Subtracting 1 from the constant term, we get:

f(x)=4x2+4x+11=4x2+4xf(x) = 4x^2 + 4x + 1 - 1 = 4x^2 + 4x

Therefore, the standard form representation of the function is f(x)=4x2+4x f(x) = 4x^2 + 4x .

Answer

f(x)=4x2+4x f(x)=4x^2+4x

Exercise #3

Find the standard representation of the following function

f(x)=(x+1)2+3 f(x)=(-x+1)^2+3

Video Solution

Step-by-Step Solution

To convert the function f(x)=(x+1)2+3 f(x) = (-x + 1)^2 + 3 to its standard form, follow these steps:

Step 1: Expand the binomial (x+1)2(-x + 1)^2.
(x+1)2=(x)2+2(x)(1)+12 (-x + 1)^2 = (-x)^2 + 2(-x)(1) + 1^2

This simplifies to:
(x)2=x2 (-x)^2 = x^2
2(x)(1)=2x 2(-x)(1) = -2x
12=1 1^2 = 1

Combining these terms gives:
(x+1)2=x22x+1 (-x + 1)^2 = x^2 - 2x + 1

Step 2: Add the constant term +3+3 to the expanded form:
f(x)=(x22x+1)+3 f(x) = (x^2 - 2x + 1) + 3

Step 3: Simplify the expression:
f(x)=x22x+1+3=x22x+4 f(x) = x^2 - 2x + 1 + 3 = x^2 - 2x + 4

Thus, the standard representation of the function is f(x)=x22x+4 f(x) = x^2 - 2x + 4 .

Answer

f(x)=x22x+4 f(x)=x^2-2x+4

Exercise #4

Find the standard representation of the following function

f(x)=(x+4)216 f(x)=(x+4)^2-16

Video Solution

Step-by-Step Solution

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

  • Step 1: Expand (x+4)2(x + 4)^2 using the formula (a+b)2=a2+2ab+b2(a + b)^2 = a^2 + 2ab + b^2.
  • Step 2: Simplify the expression by subtracting 16 from the expanded result.
  • Step 3: Write the simplified expression in the standard form.

Now, let's work through each step:
Step 1: Start with the expression given in the problem:
(x+4)2=x2+2x4+42 (x + 4)^2 = x^2 + 2 \cdot x \cdot 4 + 4^2 .

This results in:
x2+8x+16 x^2 + 8x + 16 .

Step 2: Subtract 16 from the expanded expression:
x2+8x+1616=x2+8x x^2 + 8x + 16 - 16 = x^2 + 8x .

Step 3: The standard form of the expression is now:
f(x)=x2+8x f(x) = x^2 + 8x .

Therefore, the standard representation of the function is f(x)=x2+8x f(x) = x^2 + 8x .

Answer

f(x)=x2+8x f(x)=x^2+8x

Exercise #5

Find the standard representation of the following function

f(x)=(x2)2+3 f(x)=(x-2)^2+3

Video Solution

Step-by-Step Solution

To convert the function from vertex form to standard form, follow these steps:

  • Step 1: Identify the vertex form - f(x)=(x2)2+3 f(x) = (x-2)^2 + 3 . The terms inside the parentheses represent a perfect square trinomial.
  • Step 2: Expand the square. Recall: (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 . Here, a=x a = x and b=2 b = 2 .
  • Step 3: Expand (x2)2(x-2)^2:
    (x2)2=x22x2+22=x24x+4 (x-2)^2 = x^2 - 2 \cdot x \cdot 2 + 2^2 = x^2 - 4x + 4 .
  • Step 4: Add the constant from the original function:
    f(x)=(x24x+4)+3=x24x+7 f(x) = (x^2 - 4x + 4) + 3 = x^2 - 4x + 7 .

After expanding and simplifying, we find that f(x)=x24x+7 f(x) = x^2 - 4x + 7 is the standard form of the function.

Therefore, the correct choice that matches this solution is choice 3, which is f(x)=x24x+7 f(x) = x^2 - 4x + 7 .

Answer

f(x)=x24x+7 f(x)=x^2-4x+7

Exercise #6

Find the standard representation of the following function

f(x)=(x5)210 f(x)=(x-5)^2-10

Video Solution

Step-by-Step Solution

To convert the quadratic function from vertex form to standard form, execute the following steps:

  • Step 1: Begin with the given vertex form f(x)=(x5)210 f(x) = (x-5)^2 - 10 .
  • Step 2: Expand (x5)2 (x-5)^2 using the formula (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 , which results in:

(x5)2=x22x5+52=x210x+25(x-5)^2 = x^2 - 2 \cdot x \cdot 5 + 5^2 = x^2 - 10x + 25.

  • Step 3: Replace the expanded form into the original function:

f(x)=x210x+2510f(x) = x^2 - 10x + 25 - 10.

  • Step 4: Combine like terms:

f(x)=x210x+15f(x) = x^2 - 10x + 15.

Therefore, the standard form of the function is f(x)=x210x+15 f(x) = x^2 - 10x + 15 .

Comparing with the given choices, the correct option is:

Choice 2: f(x)=x210x+15 f(x) = x^2 - 10x + 15

Answer

f(x)=x210x+15 f(x)=x^2-10x+15

Exercise #7

Find the standard representation of the following function

f(x)=(x+5)2+3 f(x)=(x+5)^2+3

Video Solution

Step-by-Step Solution

To convert the given quadratic function into its standard form, follow these steps:

  • Step 1: Expand the Binomial
    We begin with the function in vertex form: f(x)=(x+5)2+3 f(x) = (x + 5)^2 + 3 . The expression (x+5)2(x + 5)^2 can be expanded using the binomial theorem: (a+b)2=a2+2ab+b2(a + b)^2 = a^2 + 2ab + b^2.

  • Step 2: Apply the Expansion Formula
    Let a=x a = x and b=5 b = 5 . Therefore, (x+5)2=x2+2×x×5+52=x2+10x+25(x + 5)^2 = x^2 + 2 \times x \times 5 + 5^2 = x^2 + 10x + 25.

  • Step 3: Add the Constant
    Now, add the constant 3 to this expanded result: x2+10x+25+3=x2+10x+28 x^2 + 10x + 25 + 3 = x^2 + 10x + 28 .

Thus, the standard representation of the function is f(x)=x2+10x+28 f(x) = x^2 + 10x + 28 .

Given the choices, the correct answer is f(x)=x2+10x+28 f(x) = x^2 + 10x + 28 , which matches choice 2.

Answer

f(x)=x2+10x+28 f(x)=x^2+10x+28

Exercise #8

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 #9

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 #10

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 #11

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 #12

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 #13

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 #14

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 #15

Find the standard representation of the following function

f(x)=(x2)2+4 f(x)=(x-2)^2+4

Video Solution

Step-by-Step Solution

We need to convert the given function f(x)=(x2)2+4 f(x) = (x-2)^2 + 4 to standard form.

To expand (x2)2 (x-2)^2 , we use the formula (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 . Applying this to (x2)2 (x-2)^2 , we get:

  • (x2)2=x24x+4 (x-2)^2 = x^2 - 4x + 4 .

This accounts for the expanded square. Next, we add the constant term 4 4 from the original function (x2)2+4 (x-2)^2 + 4 :

  • f(x)=x24x+4+4 f(x) = x^2 - 4x + 4 + 4 .

Simplify by combining the constant terms:

  • f(x)=x24x+8 f(x) = x^2 - 4x + 8 .

The standard form of the function is thus f(x)=x24x+8 f(x) = x^2 - 4x + 8 .

Answer

f(x)=x24x+8 f(x)=x^2-4x+8

Topics learned in later sections

  1. Ways to represent a quadratic function