(x^4-5x^3-8x^2+13x-12)/(x-6)

9 min read Jun 17, 2024
(x^4-5x^3-8x^2+13x-12)/(x-6)

Solving the Polynomial Division: (x^4 - 5x^3 - 8x^2 + 13x - 12) / (x - 6)

This article aims to demonstrate the process of dividing the polynomial x^4 - 5x^3 - 8x^2 + 13x - 12 by the binomial x - 6. We will utilize the long division method to find the quotient and remainder.

Step 1: Setting Up the Long Division

Begin by setting up the problem as a long division problem:

            ____________
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 

Step 2: Dividing the Leading Terms

  • The leading term of the divisor (x - 6) is x.
  • The leading term of the dividend (x^4 - 5x^3 - 8x^2 + 13x - 12) is x^4.
  • Divide x^4 by x, which gives us x^3. Write this above the line in the quotient space.
            x^3        
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 

Step 3: Multiplying the Quotient Term

  • Multiply the quotient term (x^3) by the divisor (x - 6). This gives us x^4 - 6x^3.
            x^3        
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3

Step 4: Subtracting the Result

  • Subtract the result (x^4 - 6x^3) from the dividend. Remember to change the signs of the terms being subtracted.
            x^3        
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 

Step 5: Bringing Down the Next Term

  • Bring down the next term of the dividend (-8x^2).
            x^3        
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2

Step 6: Repeating the Process

  • Repeat steps 2-5 with the new dividend (x^3 - 8x^2).
  • Divide the leading term of the new dividend (x^3) by the leading term of the divisor (x), which gives us x^2.
  • Write this term above the line in the quotient space.
            x^3 + x^2      
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
  • Multiply the new quotient term (x^2) by the divisor (x - 6), resulting in x^3 - 6x^2.
  • Subtract this product from the current dividend, remembering to change the signs.
            x^3 + x^2      
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 
  • Bring down the next term of the dividend (+13x).
            x^3 + x^2      
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x

Step 7: Continuing the Division

  • Repeat the process with the new dividend (-2x^2 + 13x).
  • Divide the leading term of the dividend (-2x^2) by the leading term of the divisor (x), which gives us -2x.
  • Write this term above the line in the quotient space.
            x^3 + x^2 - 2x    
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x
                        -2x^2 + 12x
  • Multiply the new quotient term (-2x) by the divisor (x - 6), resulting in -2x^2 + 12x.
  • Subtract this product from the current dividend, remembering to change the signs.
            x^3 + x^2 - 2x    
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x
                        -2x^2 + 12x
                        ---------
                                x

Step 8: Final Steps

  • Bring down the last term of the dividend (-12).
            x^3 + x^2 - 2x    
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x
                        -2x^2 + 12x
                        ---------
                                x - 12
  • Divide the leading term of the new dividend (x) by the leading term of the divisor (x), which gives us 1.
  • Write this term above the line in the quotient space.
            x^3 + x^2 - 2x + 1   
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x
                        -2x^2 + 12x
                        ---------
                                x - 12
                                x - 6
  • Multiply the new quotient term (1) by the divisor (x - 6), resulting in x - 6.
  • Subtract this product from the current dividend, remembering to change the signs.
            x^3 + x^2 - 2x + 1   
x - 6 | x^4 - 5x^3 - 8x^2 + 13x - 12 
        x^4 - 6x^3
        ---------
                x^3 - 8x^2
                x^3 - 6x^2 
                ---------
                        -2x^2 + 13x
                        -2x^2 + 12x
                        ---------
                                x - 12
                                x - 6
                                --------
                                        -6

Step 9: The Result

The remainder of the division is -6. Therefore, the final result of the polynomial division can be expressed as:

(x^4 - 5x^3 - 8x^2 + 13x - 12) / (x - 6) = x^3 + x^2 - 2x + 1 - 6/(x - 6)

This can also be written as:

(x^4 - 5x^3 - 8x^2 + 13x - 12) = (x - 6)(x^3 + x^2 - 2x + 1) - 6