Quadratic Function Practice Problems - Parabola Vertex & Graph

Master quadratic functions with step-by-step practice problems. Learn to find parabola vertex, identify maximum/minimum, and determine domains of increase.

📚Master Quadratic Functions Through Interactive Practice
  • Find parabola vertex using formula X = -b/2a and symmetric points method
  • Identify maximum and minimum parabolas by analyzing coefficient 'a'
  • Calculate intersection points with X and Y axes using algebraic methods
  • Determine domains of increase and decrease for quadratic functions
  • Find positive and negative domains by analyzing parabola position
  • Solve real-world problems involving quadratic function applications

Understanding The Quadratic Function

Complete explanation with examples

The Parabola y=ax2+bx+c y=ax^2+bx+c 

This function is a quadratic function and is called a parabola.

We will focus on two main types of parabolas: maximum and minimum parabolas.

Minimum Parabola

Also called smiling or happy.

A vertex is the minimum point of the function, where YY is the lowest.

We can identify that it is a minimum parabola if the aa equation is positive.

1b - We can identify that it is a minimum parabola if the equation a is positive


Maximum Parabola

Also called sad or crying.

A vertex is the maximum point of the function, where YY is the highest.

We can identify that it is a maximum parabola if the aa equation is negative.

2b - We can identify that it is a maximum parabola if the a equation is negative

To the parabola,

the vertex marks its highest point.

How do we find it?


Detailed explanation

Practice The Quadratic Function

Test your knowledge with 17 quizzes

Determine the value of the coefficient \( a \) in the following equation:

\( -x^2+7x-9 \)

Examples with solutions for The Quadratic Function

Step-by-step solutions included
Exercise #1

y=x2+10x y=x^2+10x

Step-by-Step Solution

Here we have a quadratic equation.

A quadratic equation is always constructed like this:

 

y=ax2+bx+c y = ax²+bx+c

 

Where a, b, and c are generally already known to us, and the X and Y points need to be discovered.

Firstly, it seems that in this formula we do not have the C,

Therefore, we understand it is equal to 0.

c=0 c = 0

 

a is the coefficient of X², here it does not have a coefficient, therefore

a=1 a = 1

 

b=10 b= 10

is the number that comes before the X that is not squared.

 

Answer:

a=1,b=10,c=0 a=1,b=10,c=0

Video Solution
Exercise #2

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

Step-by-Step Solution

To solve this problem, we will follow these steps:

  • Step 1: Identify each term in the given function y=2x2+3y = 2x^2 + 3.
  • Step 2: Compare the equation to the standard quadratic form y=ax2+bx+cy = ax^2 + bx + c.
  • Step 3: Determine the coefficients aa, bb, and cc.
  • Step 4: Match these coefficients to the correct multiple-choice option.

Step 1: The given function is y=2x2+3y = 2x^2 + 3. There is no xx term present.

Step 2: Compare this with the standard form y=ax2+bx+cy = ax^2 + bx + c:

  • The coefficient of x2x^2 is a=2a = 2.
  • The coefficient of xx is b=0b = 0 because there is no xx term.
  • The constant term is c=3c = 3.

Step 3: Therefore, the coefficients are a=2a = 2, b=0b = 0, and c=3c = 3.

Step 4: Review the multiple-choice options provided:

  • Choice 1: a=0a = 0, b=2b = 2, c=3c = 3
  • Choice 2: a=0a = 0, b=3b = 3, c=2c = 2
  • Choice 3: a=2a = 2, b=0b = 0, c=3c = 3
  • Choice 4: a=3a = 3, b=0b = 0, c=2c = 2

The correct choice is Choice 3: a=2a = 2, b=0b = 0, c=3c = 3.

Therefore, the solution to the problem is the values a=2a = 2, b=0b = 0, c=3c = 3 which correspond to choice 3.

Answer:

a=2,b=0,c=3 a=2,b=0,c=3

Video Solution
Exercise #3

Identify the coefficients based on the following equation

y=x26x+4 y=x^2-6x+4

Step-by-Step Solution

To solve this problem, we'll clearly delineate the given expression and compare it to the standard quadratic form:

  • Step 1: Recognize the standard form of a quadratic equation as y=ax2+bx+c y = ax^2 + bx + c .
  • Step 2: Compare the given equation y=x26x+4 y = x^2 - 6x + 4 to the standard form.
  • Step 3: Identify coefficients:
    - The coefficient of x2 x^2 is a=1 a = 1 .
    - The coefficient of x x is b=6 b = -6 .
    - The constant term is c=4 c = 4 .

Therefore, the coefficients for the quadratic function y=x26x+4 y = x^2 - 6x + 4 are a=1 a = 1 , b=6 b = -6 , and c=4 c = 4 .

Among the provided choices, choice 3: a=1,b=6,c=4 a=1,b=-6,c=4 is the correct one.

Answer:

a=1,b=6,c=4 a=1,b=-6,c=4

Video Solution
Exercise #4

Identify the coefficients based on the following equation

y=2x23x6 y=2x^2-3x-6

Step-by-Step Solution

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

  • Identify the given quadratic function.
  • Match it with the standard form of a quadratic equation y=ax2+bx+cy = ax^2 + bx + c.
  • Extract the values of aa, bb, and cc directly from the comparison.

Now, let's work through each step:
Step 1: The given quadratic function is y=2x23x6y = 2x^2 - 3x - 6.
Step 2: The standard form of a quadratic equation is y=ax2+bx+cy = ax^2 + bx + c.
Step 3: By matching the given quadratic function with the standard form:

- The coefficient of x2x^2 is 22, so a=2a = 2.
- The coefficient of xx is 3-3, so b=3b = -3.
- The constant term is 6-6, so c=6c = -6.

Therefore, the solution to the problem is a=2a = 2, b=3b = -3, c=6c = -6.

Answer:

a=2,b=3,c=6 a=2,b=-3,c=-6

Video Solution
Exercise #5

Identify the coefficients based on the following equation

y=3x281 y=3x^2-81

Step-by-Step Solution

To solve this problem, we will identify values of aa, bb, and cc in the quadratic function:

  • Step 1: Note the given equation y=3x281y = 3x^2 - 81.
  • Step 2: Compare it to the standard quadratic form y=ax2+bx+cy = ax^2 + bx + c.
  • Step 3: Match coefficients to find aa, bb, and cc.

Now, let's work through each step:
Step 1: The given equation is y=3x281y = 3x^2 - 81.
Step 2: Compare this to the standard form, y=ax2+bx+cy = ax^2 + bx + c. In this equation:
- The coefficient of x2x^2 is 3, hence a=3a = 3.
- There is no xx term, which means b=0b = 0.
- The constant term is 81-81, hence c=81c = -81.

Therefore, the solution to the problem is a=3,b=0,c=81 a = 3, b = 0, c = -81 .

Answer:

a=3,b=0,c=81 a=3,b=0,c=-81

Video Solution

Frequently Asked Questions

How do you find the vertex of a parabola y = ax² + bx + c?

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Use the vertex formula X = -b/2a to find the x-coordinate. Then substitute this value back into the original equation to find the y-coordinate. Alternatively, you can use two symmetric points and find their midpoint.

What determines if a parabola opens upward or downward?

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The coefficient 'a' in y = ax² + bx + c determines the direction. If a > 0, the parabola opens upward (minimum/smiling). If a < 0, the parabola opens downward (maximum/sad).

How many x-intercepts can a quadratic function have?

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A parabola can have 0, 1, or 2 x-intercepts. To find them, set y = 0 and solve the quadratic equation using factoring, completing the square, or the quadratic formula.

What is the difference between domains of increase and decrease?

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Domain of increase: x-values where the parabola rises (y increases as x increases). Domain of decrease: x-values where the parabola falls (y decreases as x increases). The vertex marks where this behavior changes.

How do you find positive and negative domains of a parabola?

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1. Find x-intercepts by setting y = 0 2. Plot the parabola 3. Positive domain: x-values where graph is above x-axis (y > 0) 4. Negative domain: x-values where graph is below x-axis (y < 0)

What is the y-intercept of a quadratic function?

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The y-intercept is found by setting x = 0 in the equation y = ax² + bx + c. This gives y = c, so the y-intercept is always the constant term 'c'.

Why is the vertex important in quadratic functions?

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The vertex represents the maximum or minimum point of the parabola. It's where the function changes from increasing to decreasing (or vice versa) and is crucial for understanding the function's behavior and solving optimization problems.

How do you determine if a quadratic function has real solutions?

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Calculate the discriminant b² - 4ac. If positive: 2 real solutions (2 x-intercepts). If zero: 1 real solution (1 x-intercept). If negative: no real solutions (no x-intercepts).

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