(x^3-13x-12)/(x-4)

4 min read Jun 17, 2024
(x^3-13x-12)/(x-4)

Simplifying the Expression (x^3 - 13x - 12) / (x - 4)

This expression represents a rational function, which is a fraction where both the numerator and denominator are polynomials. To simplify this expression, we can utilize polynomial long division.

Polynomial Long Division

  1. Set up the division:

         ________
    x - 4 | x^3 + 0x^2 - 13x - 12 
    
  2. Divide the leading terms:

    • The leading term of the divisor (x - 4) is x.
    • The leading term of the dividend (x^3) is x^3.
    • Divide x^3 by x, which gives x^2.
    • Write x^2 above the division line.
         x^2_______
    x - 4 | x^3 + 0x^2 - 13x - 12 
    
  3. Multiply the quotient by the divisor:

    • Multiply x^2 by (x - 4), which gives x^3 - 4x^2.
    • Write the result below the dividend.
         x^2_______
    x - 4 | x^3 + 0x^2 - 13x - 12 
            x^3 - 4x^2
    
  4. Subtract:

    • Subtract the product from the dividend. Remember to change the signs of the terms you are subtracting.
         x^2_______
    x - 4 | x^3 + 0x^2 - 13x - 12 
            x^3 - 4x^2
            ---------
                  4x^2 - 13x 
    
  5. Bring down the next term:

    • Bring down the next term from the dividend (-13x).
         x^2_______
    x - 4 | x^3 + 0x^2 - 13x - 12 
            x^3 - 4x^2
            ---------
                  4x^2 - 13x - 12 
    
  6. Repeat steps 2-5:

    • Divide the leading term of the new dividend (4x^2) by the leading term of the divisor (x), which gives 4x.
    • Write 4x above the division line.
    • Multiply 4x by (x - 4), giving 4x^2 - 16x.
    • Subtract this product from the new dividend.
         x^2 + 4x_____
    x - 4 | x^3 + 0x^2 - 13x - 12 
            x^3 - 4x^2
            ---------
                  4x^2 - 13x - 12 
                  4x^2 - 16x
                  ---------
                           3x - 12 
    
  7. Repeat steps 2-5 again:

    • Divide the leading term of the new dividend (3x) by the leading term of the divisor (x), which gives 3.
    • Write 3 above the division line.
    • Multiply 3 by (x - 4), giving 3x - 12.
    • Subtract this product from the new dividend.
         x^2 + 4x + 3__
    x - 4 | x^3 + 0x^2 - 13x - 12 
            x^3 - 4x^2
            ---------
                  4x^2 - 13x - 12 
                  4x^2 - 16x
                  ---------
                           3x - 12 
                           3x - 12
                           ---------
                                 0
    
  8. The result:

    • The quotient is x^2 + 4x + 3.
    • The remainder is 0.

Therefore, (x^3 - 13x - 12) / (x - 4) simplifies to x^2 + 4x + 3.

Conclusion

This simplification demonstrates the effectiveness of polynomial long division for dividing polynomials. The result shows that the original rational function can be expressed as a simpler polynomial, which may be useful in further analysis or calculations.