Quadratic Formula Practice Problems - Step-by-Step Solutions

Master the quadratic formula with guided practice problems. Learn to solve ax²+bx+c=0 equations, identify coefficients, and understand discriminants through examples.

📚What You'll Master in This Practice Session
  • Identify coefficients a, b, and c in quadratic equations
  • Apply the quadratic formula X = (-b ± √(b²-4ac)) / 2a correctly
  • Calculate discriminant values to predict number of solutions
  • Solve complete quadratic equations with three parameters
  • Interpret parabola intersection points on coordinate axes
  • Check solutions by substituting back into original equations

Understanding The Quadratic Formula

Complete explanation with examples

What is a quadratic equation?

Quadratic equations (also called second degree equations) contain three numbers called parameters:

  • Parameter a a represents the position of the vertex of the parabola on the Y Y axis. A parabola can have a maximum vertex, or a minimum vertex (depending on if the parabola opens upwards or downwards).
  • Parameter b b represents the position of the vertex of the parabola on the X X axis.
  • Parameter c c represents the point of intersection of the parabola with the Y Y axis.

These three parameters are expressed in quadratic equations as follows:

aX2+bX+c=0 aX^2+bX+c=0

They are called the coefficients of the equation.

So, how do we find the value of X X ?

To find X X and be able to solve the quadratic equation, all we need to do is to input the parameters (the number values of a, b and c) from the equation into the quadratic formula, and solve for X X .

For example:

3X2+8X+4=0 3X^2+8X+4=0

Detailed explanation

Practice The Quadratic Formula

Test your knowledge with 26 quizzes

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


what is the value of \( c \) in this quadratic equation:

\( y=5+3x^2 \)

Examples with solutions for The Quadratic Formula

Step-by-step solutions included
Exercise #1

a = Coefficient of x²

b = Coefficient of x

c = Coefficient of the independent number


what is the value of a a in the equation

y=3x10+5x2 y=3x-10+5x^2

Step-by-Step Solution

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

  • Step 1: Rewrite the given equation in standard quadratic form if necessary.
  • Step 2: Identify the term with x2 x^2 in the equation.
  • Step 3: Extract the coefficient of x2 x^2 as a a .

Now, let's work through each step:
Step 1: The provided equation is y=3x10+5x2 y = 3x - 10 + 5x^2 . Although it's not initially in standard form, observation shows that the x2 x^2 term is clearly present.
Step 2: Locate the x2 x^2 term: in our equation, this term is 5x2 5x^2 .
Step 3: The coefficient of x2 x^2 is 5 5 . Hence, a=5 a = 5 .

Therefore, the coefficient of x2 x^2 , or a a , is a=5 a = 5 .

Answer:

a=5 a=5

Video Solution
Exercise #2

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


x2+4x5=0 x^2+4x-5=0

What are the components of the equation?

Step-by-Step Solution

The quadratic equation we have is x2+4x5=0 x^2 + 4x - 5 = 0 .

We'll compare this with the general form of a quadratic equation: ax2+bx+c=0 ax^2 + bx + c = 0 .

1. Identify a a : The coefficient of x2 x^2 in the given equation is 1 1 . Therefore, a=1 a = 1 .

2. Identify b b : The coefficient of x x in the given equation is 4 4 . Therefore, b=4 b = 4 .

3. Identify c c : The constant term in the given equation is 5 -5 . Therefore, c=5 c = -5 .

Thus, the components of the equation are:

  • a=1 a = 1
  • b=4 b = 4
  • c=5 c = -5

The correct answer to this problem, matching choice id 3, is:

a=1 a=1 b=4 b=4 c=5 c=-5

Answer:

a=1 a=1 b=4 b=4 c=5 c=-5

Video Solution
Exercise #3

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


10x2+5+20x=0 10x^2+5+20x=0

What are the components of the equation?

Step-by-Step Solution

To determine the components of the quadratic equation, follow these steps:

  • Step 1: Recognize the standard form of a quadratic equation, which is ax2+bx+c=0 ax^2 + bx + c = 0 .
  • Step 2: Compare the given equation 10x2+20x+5=0 10x^2 + 20x + 5 = 0 to the standard form.
  • Step 3: Identify the coefficients:
    - The term 10x2 10x^2 indicates that a=10 a = 10 .
    - The term 20x 20x indicates that b=20 b = 20 .
    - The term 5 5 is the constant term, so c=5 c = 5 .

Therefore, the components of the equation are:

a=10 a = 10 , b=20 b = 20 , c=5 c = 5 .

The correct answer among the choices provided is the one that correctly identifies these coefficients:

a=10 a=10 b=20 b=20 c=5 c=5

Therefore, the correct choice is Choice 4.

Answer:

a=10 a=10 b=20 b=20 c=5 c=5

Video Solution
Exercise #4

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


what is the value of a a in the equation

y=x23x+1 y=-x^2-3x+1

Step-by-Step Solution

To determine the coefficient a a in the given quadratic equation y=x23x+1 y = -x^2 - 3x + 1 , follow these steps:

  • Step 1: Recognize the form of the quadratic equation as y=ax2+bx+c y = ax^2 + bx + c .
  • Step 2: Identify the x2 x^2 term in the equation y=x23x+1 y = -x^2 - 3x + 1 .
  • Step 3: Determine the coefficient of the x2 x^2 term, which is in front of x2 x^2 .

In the equation y=x23x+1 y = -x^2 - 3x + 1 , the term involving x2 x^2 is x2-x^2, where the coefficient a a is clearly 1-1.

Hence, the value of a a is a=1 a = -1 .

Answer:

a=1 a=-1

Video Solution
Exercise #5

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


56x2+12x=0 5-6x^2+12x=0

What are the components of the equation?

Step-by-Step Solution

Let's solve this problem step-by-step by identifying the coefficients of the quadratic equation:

First, examine the given equation:

56x2+12x=05 - 6x^2 + 12x = 0

To make it easier to identify the coefficients, we rewrite the equation in the standard quadratic form:

6x2+12x+5=0-6x^2 + 12x + 5 = 0

In this expression, we can now directly identify the coefficients:

  • The coefficient of x2 x^2 (quadratic term) is a=6 a = -6 .
  • The coefficient of x x (linear term) is b=12 b = 12 .
  • The constant term (independent number) is c=5 c = 5 .

Thus, the components of the quadratic equation are:

a=6 a = -6 , b=12 b = 12 , c=5 c = 5

By comparing these values to the multiple-choice options, we can determine that the correct choice is:

Choice 4: a=6 a = -6 , b=12 b = 12 , c=5 c = 5

Therefore, the final solution is:

a=6 a = -6 , b=12 b = 12 , c=5 c = 5 .

Answer:

a=6 a=-6 b=12 b=12 c=5 c=5

Video Solution

Frequently Asked Questions

What is the quadratic formula and when do I use it?

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The quadratic formula is X = (-b ± √(b²-4ac)) / 2a, used to solve second-degree equations in the form ax²+bx+c=0. Use it when you can't easily factor the quadratic equation or when completing the square becomes too complex.

How do I identify the coefficients a, b, and c in a quadratic equation?

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In the standard form ax²+bx+c=0: 'a' is the coefficient of X², 'b' is the coefficient of X, and 'c' is the constant term. For example, in 3X²+8X+4=0, a=3, b=8, c=4. Remember that 'a' cannot equal zero.

What does the discriminant tell me about solutions?

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The discriminant (b²-4ac) predicts the number of solutions: If positive (>0), there are two real solutions; if zero (=0), there's one solution; if negative (<0), there are no real solutions. This corresponds to how many times the parabola crosses the X-axis.

Why do quadratic equations sometimes have two solutions?

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Quadratic equations represent parabolas, which are U-shaped curves. A parabola can intersect the X-axis at two points, one point, or no points at all. Each intersection point represents a solution to the equation, which is why you can have zero, one, or two solutions.

What's the difference between quadratic equations and linear equations?

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Linear equations have variables to the first power (like 2x+3=0) and graph as straight lines, while quadratic equations have variables to the second power (like x²+2x+1=0) and graph as curved parabolas. Quadratic equations can have up to two solutions, while linear equations have exactly one solution.

How do I solve quadratic equations step by step?

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Follow these steps: 1) Write the equation in standard form ax²+bx+c=0, 2) Identify coefficients a, b, and c, 3) Substitute into the quadratic formula X = (-b ± √(b²-4ac)) / 2a, 4) Calculate the discriminant under the square root, 5) Solve for both + and - cases, 6) Check your answers by substituting back.

Can I use the quadratic formula for incomplete quadratic equations?

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Yes, but you need to identify missing terms correctly. For equations like X²+5X=0, you have a=1, b=5, c=0. For equations like X²-4=0, you have a=1, b=0, c=-4. Always ensure you're working with the complete form ax²+bx+c=0 before applying the formula.

What should I do if I get a negative number under the square root?

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A negative discriminant means the equation has no real solutions - the parabola doesn't intersect the X-axis. Double-check your calculations first, but if correct, simply state 'no real solutions' or 'no solution' as your answer. This is a valid mathematical result.

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