Quadratic Equations Practice Problems - Solve by 3 Methods

Master solving quadratic equations with step-by-step practice problems using trinomial factoring, quadratic formula, and completing the square methods.

📚Master Three Essential Methods for Solving Quadratic Equations
  • Factor trinomials using the ac method to find quadratic solutions
  • Apply the quadratic formula to solve ax²+bx+c=0 equations systematically
  • Complete the square method for quadratic functions with any coefficients
  • Identify when to use each method based on coefficient patterns
  • Solve real-world problems involving quadratic equations and functions
  • Verify solutions by substitution and graphical interpretation

Understanding Solving Quadratic Equations

Complete explanation with examples

Methods for solving a quadratic function

In this article, we will learn the three most common ways to solve a quadratic function easily and quickly.

  1. Trinomial
  2. Quadratic Formula
  3. Completing the Square

Reminder:

The basic quadratic function equation is:
Y=ax2+bx+cY=ax^2+bx+c

When:
a a   - the coefficient of X2X^2
b b   - the coefficient of XX
cc - the constant term

  • aa must be different from 00
  • bb or cc can be 00
  • a,b,ca,b,c can be negative/positive
  • The quadratic function can also look like this:
    • Y=ax2Y=ax^2
    • Y=ax2+bxY=ax^2+bx
    • Y=ax2+cY=ax^2+c
Detailed explanation

Practice Solving Quadratic Equations

Test your knowledge with 28 quizzes

Solve the following equation:

\( x^2-4x+4=0 \)

Examples with solutions for Solving Quadratic Equations

Step-by-step solutions included
Exercise #1

a = coefficient of x²

b = coefficient of x

c = coefficient of the constant term


What is the value of c c in the function y=x2+25x y=-x^2+25x ?

Step-by-Step Solution

Let's recall the general form of the quadratic function:

y=ax2+bx+c y=ax^2+bx+c The function given in the problem is:

y=x2+25x y=-x^2+25x c c is the free term (meaning the coefficient of the term with power 0),

In the function in the problem there is no free term,

Therefore, we can identify that:

c=0 c=0 Therefore, the correct answer is answer A.

Answer:

c=0 c=0

Video Solution
Exercise #2

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


what is the value ofb b in this quadratic equation:

y=4x216 y=4x^2-16

Step-by-Step Solution

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

  • Identify the given information and the standard quadratic form
  • Compare the given equation to this standard form
  • Extract the coefficients a a , b b , and c c and find b b

Now, let's work through each step:
Step 1: The problem provides us with the equation y=4x216 y = 4x^2 - 16 . It's already in a form where we can identify the coefficients.
Step 2: Recall the standard form of a quadratic equation is ax2+bx+c ax^2 + bx + c . Compare this form to the equation y=4x216 y = 4x^2 - 16 .
Step 3: By comparison, the coefficient of x2 x^2 (which is a a ) is 4. There is no x x term explicitly present, implying that b=0 b = 0 . The constant c c is -16.
Therefore, after comparison and identification, it becomes clear that the value of b b in the equation is b=0 b = 0 .

Answer:

b=0 b=0

Video Solution
Exercise #3

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


what is the value of c c in this quadratic equation:

y=5+3x2 y=5+3x^2

Step-by-Step Solution

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

  • Step 1: Compare the given equation y=5+3x2 y = 5 + 3x^2 to the standard form ax2+bx+c ax^2 + bx + c .
  • Step 2: Identify the terms corresponding to a a , b b , and c c .

Now, let's work through each step:
Step 1: The given equation is y=5+3x2 y = 5 + 3x^2 . Rearranging it in the standard form, we have y=3x2+0x+5 y = 3x^2 + 0\cdot x + 5 .

Step 2: From this arrangement, it's clear that:
- a=3 a = 3 (the coefficient of x2 x^2 )
- b=0 b = 0 (there is no x x term, so its coefficient is 0)
- c=5 c = 5 (the constant term)

Therefore, the value of c c is  c=5\ c=5 .

Answer:

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 b b in the equation

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

Step-by-Step Solution

To solve this problem, we need to identify the coefficient of x x in the given quadratic equation. The equation given is y=3x2+10x y = 3x^2 + 10 - x . Let’s rearrange this equation to match the standard form of a quadratic equation ax2+bx+c ax^2 + bx + c .

The given equation can be rewritten as:

y=3x2x+10 y = 3x^2 - x + 10

Here, we can identify the coefficients:

  • a=3 a = 3 (for x2 x^2 )
  • b=1 b = -1 (for x x )
  • c=10 c = 10 (the constant term)

Therefore, the value of b b , the coefficient of x x , is 1 -1 .

Answer:

b=1 b=-1

Video Solution
Exercise #5

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

Frequently Asked Questions

What are the three main methods for solving quadratic equations?

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The three main methods are: 1) Trinomial factoring (finding two numbers that multiply to ac and add to b), 2) Quadratic formula (x = [-b ± √(b²-4ac)]/2a), and 3) Completing the square (rewriting as a perfect square trinomial).

When should I use the trinomial method vs quadratic formula?

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Use trinomial factoring when a=1 and the equation factors easily with integer solutions. Use the quadratic formula when factoring is difficult or when you need exact decimal solutions. The quadratic formula works for all quadratic equations.

How do I know if a quadratic equation can be factored?

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Check if the discriminant (b²-4ac) is a perfect square. If it is, the equation factors with rational solutions. Also look for common factors first, and see if you can find two numbers that multiply to ac and add to b.

What is the discriminant and why is it important?

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The discriminant is b²-4ac from under the square root in the quadratic formula. If it's positive, there are two real solutions. If zero, one repeated solution. If negative, no real solutions (complex solutions only).

How do I complete the square for ax²+bx+c when a≠1?

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First factor out 'a' from the x terms: a(x² + (b/a)x) + c. Then complete the square inside parentheses by adding and subtracting (b/2a)². Finally, factor the perfect square trinomial and simplify.

What are common mistakes when solving quadratic equations?

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Common errors include: forgetting the ± in the quadratic formula, sign errors when completing the square, not checking if a=0 (making it linear), and forgetting to set the equation equal to zero before factoring.

Can quadratic equations have no real solutions?

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Yes, when the discriminant (b²-4ac) is negative, there are no real number solutions. The parabola doesn't cross the x-axis. However, there are still complex number solutions using imaginary numbers.

How do I check if my quadratic equation solutions are correct?

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Substitute each solution back into the original equation. If both sides equal zero, your solution is correct. You can also verify by graphing - the solutions are where the parabola crosses the x-axis.

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