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

a = coefficient of x²

b = coefficient of x

c = coefficient of the independent number


\( -8x^2-5x+9=0 \)

What are the components of the equation?

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 independent number

Identifies a,b,c

5x2+6x8=0 5x^2+6x-8=0

Step-by-Step Solution

To identify the coefficients from the quadratic equation 5x2+6x8=0 5x^2 + 6x - 8 = 0 , follow these steps:

  • Standard Form of Quadratic Equation: Compare 5x2+6x85x^2 + 6x - 8 with the standard form ax2+bx+c=0ax^2 + bx + c = 0.
  • Identify aa, bb, and cc:
    • a=5 a = 5 : The coefficient of x2x^2.
    • b=6 b = 6 : The coefficient of xx.
    • c=8 c = -8 : The constant term (independent of xx).

Therefore, from the equation 5x2+6x8=0 5x^2 + 6x - 8 = 0 , the coefficients are identified as a=5 a=5 , b=6 b=6 , and c=8 c=-8 .

Comparing with choices, we find that choice 2 is correct: a=5 a=5 , b=6 b=6 , c=8 c=-8 .

Thus, the coefficients are identified as a=5 a=5 , b=6 b=6 , c=8 c=-8 .

Answer:

a=5 a=5 b=6 b=6 c=8 c=-8

Video Solution
Exercise #2

Solve the following equation:

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

Step-by-Step Solution

The parameters are expressed in the quadratic equation as follows:

aX2+bX+c=0

 

We substitute into the formula:

 

-5±√(5²-4*1*4) 
          2

 

-5±√(25-16)
         2

 

-5±√9
    2

 

-5±3
   2

 

The symbol ± means that we have to solve this part twice, once with a plus and a second time with a minus,

This is how we later get two results.

 

-5-3 = -8
-8/2 = -4

 

-5+3 = -2
-2/2 = -1

 

And thus we find out that X = -1, -4

Answer:

x1=1 x_1=-1 x2=4 x_2=-4

Video Solution
Exercise #3

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 #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


what is the value of b b in the equation

y=2x3x2+1 y=2x-3x^2+1

Step-by-Step Solution

To solve this problem, we need to identify the coefficients in the given quadratic equation:

  • The equation provided is y=2x3x2+1 y = 2x - 3x^2 + 1 .
  • The standard form of a quadratic equation is ax2+bx+c ax^2 + bx + c .
  • From the equation, identify:
    • The ax2 ax^2 term is 3x2 -3x^2 , indicating a=3 a = -3 .
    • The bx bx term is 2x 2x , indicating b=2 b = 2 .
    • The constant term c c is 1 1 .

Thus, the coefficient b b in the equation y=2x3x2+1 y = 2x - 3x^2 + 1 is b=2 b = 2 , which corresponds to choice 1.

Answer:

b=2 b=2

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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