Examples with solutions for The Quadratic Formula: Factoring Out the Greatest Common Factor (GCF)

Exercise #1

What is the value of x?

x4x3=2x2 x^4-x^3=2x^2

Video Solution

Step-by-Step Solution

To solve the problem x4x3=2x2 x^4 - x^3 = 2x^2 , let's proceed as follows:

  • Step 1: Set the equation to zero.
    x4x32x2=0 x^4 - x^3 - 2x^2 = 0
  • Step 2: Factor out the greatest common factor.
    The common factor among all terms is x2 x^2 .
    Factoring out x2 x^2 gives:
    x2(x2x2)=0 x^2(x^2 - x - 2) = 0
  • Step 3: Solve the factors.
    This equation breaks into two factors that can be solved separately:
    • x2=0 x^2 = 0
    • x2x2=0 x^2 - x - 2 = 0
  • Step 4: Solve x2=0 x^2 = 0 .
    Since x2=0 x^2 = 0 , we get:
    x=0 x = 0
  • Step 5: Solve x2x2=0 x^2 - x - 2 = 0 .
    This can be factored further. We look for two numbers that multiply to 2-2 and add up to 1-1.
    These numbers are 2-2 and 11, so we factor as:
    (x2)(x+1)=0 (x - 2)(x + 1) = 0
  • Step 6: Solve the quadratic factors.
    Set each factor equal to zero:
    • x2=0x=2 x - 2 = 0 \Rightarrow x = 2
    • x+1=0x=1 x + 1 = 0 \Rightarrow x = -1

The solutions to the equation x4x3=2x2 x^4 - x^3 = 2x^2 are x=1,0,2 x = -1, 0, 2 .

Therefore, the correct answer is:

x=1,2,0 x = -1, 2, 0

Answer

x=1,2,0 x=-1,2,0

Exercise #2

x3=x2+2x x^3=x^2+2x

Video Solution

Step-by-Step Solution

To solve the problem x3=x2+2x x^3 = x^2 + 2x , follow these steps:

  • Step 1: Re-arrange the equation to have all terms on one side:
    x3x22x=0 x^3 - x^2 - 2x = 0 .
  • Step 2: Factor out the greatest common factor (GCF), which is x x :
    x(x2x2)=0 x(x^2 - x - 2) = 0 .
  • Step 3: Factor the quadratic expression x2x2 x^2 - x - 2 :
    The factors of 2-2 that add up to 1-1 are 2-2 and 11. Thus, x2x2=(x2)(x+1) x^2 - x - 2 = (x-2)(x+1) .
  • Step 4: Combine the factored terms:
    x(x2)(x+1)=0 x(x-2)(x+1) = 0 .

Each factor can be set to zero to find the solutions:

  • x=0 x = 0 .
  • x2=0 x - 2 = 0 , so x=2 x = 2 .
  • x+1=0 x + 1 = 0 , so x=1 x = -1 .

The solutions to the equation are x=0,1,2 x = 0, -1, 2 .

Therefore, the correct choice from the given options is:
x=0,1,2 x = 0, -1, 2 .

Answer

x=0,1,2 x=0,-1,2

Exercise #3

x37x2+6x=0 x^3-7x^2+6x=0

Video Solution

Step-by-Step Solution

To solve the given cubic equation x37x2+6x=0 x^3 - 7x^2 + 6x = 0 , follow these steps:

  • Step 1: Identify that the equation can be factored by its Greatest Common Factor (GCF).

There is an x x common in all terms: x(x27x+6)=0 x(x^2 - 7x + 6) = 0

  • Step 2: Factor the quadratic expression x27x+6 x^2 - 7x + 6 .

Look for two numbers that multiply to 6 6 (the constant term) and add up to 7 -7 (the coefficient of the linear term). The numbers are 1 -1 and 6 -6 . Thus:

x27x+6=(x1)(x6) x^2 - 7x + 6 = (x - 1)(x - 6)

  • Step 3: Set each factor equal to zero to solve for x x .

Now that the equation is fully factored as x(x1)(x6)=0 x(x - 1)(x - 6) = 0 , apply the zero product property:

x=0 x = 0 , x1=0 x - 1 = 0 (so x=1 x = 1 ), x6=0 x - 6 = 0 (so x=6 x = 6 )

Thus, the solutions to the equation x37x2+6x=0 x^3 - 7x^2 + 6x = 0 are x=0 x = 0 , x=1 x = 1 , and x=6 x = 6 .

Answer

x=0,1,6 x=0,1,6

Exercise #4

x3+x212x=0 x^3+x^2-12x=0

Video Solution

Step-by-Step Solution

To solve the equation x3+x212x=0 x^3 + x^2 - 12x = 0 , follow these steps:

  • Step 1: Factor out the greatest common factor. The common factor here is x x .
  • Step 2: The equation becomes x(x2+x12)=0 x(x^2 + x - 12) = 0 .
  • Step 3: Apply the zero-product property. This gives us two equations to solve: x=0 x = 0 and x2+x12=0 x^2 + x - 12 = 0 .
  • Step 4: Solve x=0 x = 0 . This is a straightforward solution: x=0 x = 0 .
  • Step 5: Solve the quadratic equation x2+x12=0 x^2 + x - 12 = 0 . We will factor it:
    • Factor as (x3)(x+4)=0 (x - 3)(x + 4) = 0 .
    • Set each factor equal to zero: x3=0 x - 3 = 0 or x+4=0 x + 4 = 0 .
    • Solving these, we obtain x=3 x = 3 and x=4 x = -4 .

Therefore, the solutions to the equation are x=0 x = 0 , x=3 x = 3 , and x=4 x = -4 .

Thus, the complete solution set for x x is x=0,3,4 x = 0, 3, -4 .

Answer

x=0,3,4 x=0,3,-4

Exercise #5

3x310x2+7x=0 3x^3-10x^2+7x=0

Video Solution

Answer

x=0,1,73 x=0,1,\frac{7}{3}