Obtain all other zeroes of the polynomial x4 2x3 13x2 38x 24, if two of its zeroes are 1 and 2

Changes made to your input should not affect the solution:

 (1): "x2"   was replaced by   "x^2".  2 more similar replacement(s).


Step  1  :

Equation at the end of step  1  :

((((x4)+(2•(x3)))-13x2)-38x)-24

Equation at the end of step  2  :

((((x4) + 2x3) - 13x2) - 38x) - 24

Step  3  :

Polynomial Roots Calculator :

 3.1    Find roots (zeroes) of :       F(x) = x4+2x3-13x2-38x-24
Polynomial Roots Calculator is a set of methods aimed at finding values of  x  for which   F(x)=0  

Rational Roots Test is one of the above mentioned tools. It would only find Rational Roots that is numbers  x  which can be expressed as the quotient of two integers

The Rational Root Theorem states that if a polynomial zeroes for a rational number  P/Q   then  P  is a factor of the Trailing Constant and  Q  is a factor of the Leading Coefficient

In this case, the Leading Coefficient is  1  and the Trailing Constant is The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant : Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      0.00    x+1 
     -2     1      -2.00      0.00    x+2 
     -3     1      -3.00      0.00    x+3 
     -4     1      -4.00      48.00   
     -6     1      -6.00      600.00   
     -8     1      -8.00      2520.00   
     -12     1     -12.00     15840.00   
     -24     1     -24.00     297528.00   
     1     1      1.00      -72.00   
     2     1      2.00      -120.00   
     3     1      3.00      -120.00   
     4     1      4.00      0.00    x-4 
     6     1      6.00      1008.00   
     8     1      8.00      3960.00   
     12     1      12.00     21840.00   
     24     1      24.00     351000.00   


The Factor Theorem states that if P/Q is root of a polynomial then this polynomial can be divided by q*x-p Note that q and p originate from P/Q reduced to its lowest terms In our case this means that

   x4+2x3-13x2-38x-24 


can be divided by 4 different polynomials,including by  x-4 

Polynomial Long Division :

 3.2    Polynomial Long Division
Dividing :

 x4+2x3-13x2-38x-24                               ("Dividend")

By         :    x-4    ("Divisor")

dividend  x4 + 2x3 - 13x2 - 38x - 24 
- divisor * x3   x4 - 4x3       
remainder    6x3 - 13x2 - 38x - 24 
- divisor * 6x2     6x3 - 24x2     
remainder      11x2 - 38x - 24 
- divisor * 11x1       11x2 - 44x   
remainder        6x - 24 
- divisor * 6x0         6x - 24 
remainder         0

Quotient :  x3+6x2+11x+6  Remainder:  0 

Polynomial Roots Calculator :

 3.3    Find roots (zeroes) of :       F(x) = x3+6x2+11x+6

     See theory in step 3.1


In this case, the Leading Coefficient is  1  and the Trailing Constant is The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant : Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      0.00    x+1 
     -2     1      -2.00      0.00    x+2 
     -3     1      -3.00      0.00    x+3 
     -6     1      -6.00      -60.00   
     1     1      1.00      24.00   
     2     1      2.00      60.00   
     3     1      3.00      120.00   
     6     1      6.00      504.00   


The Factor Theorem states that if P/Q is root of a polynomial then this polynomial can be divided by q*x-p Note that q and p originate from P/Q reduced to its lowest terms In our case this means that

   x3+6x2+11x+6 


can be divided by 3 different polynomials,including by  x+3 

Polynomial Long Division :

 3.4    Polynomial Long Division
Dividing :

 x3+6x2+11x+6                               ("Dividend")

By         :    x+3    ("Divisor")

dividend  x3 + 6x2 + 11x + 6 
- divisor * x2   x3 + 3x2     
remainder    3x2 + 11x + 6 
- divisor * 3x1     3x2 + 9x   
remainder      2x + 6 
- divisor * 2x0       2x + 6 
remainder       0

Quotient :  x2+3x+2  Remainder:  0 

Trying to factor by splitting the middle term

 3.5     Factoring  x2+3x+2 

The first term is,  x2  its coefficient is  1 .


The middle term is,  +3x  its coefficient is  3 .
The last term, "the constant", is  +2 

Step-1 : Multiply the coefficient of the first term by the constant   1 • 2 = 2 

Step-2 : Find two factors of  2  whose sum equals the coefficient of the middle term, which is   3 .


     -2   +   -1   =   -3
     -1   +   -2   =   -3
     1   +   2   =   3   That's it


Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  1  and  2 
                     x2 + 1x + 2x + 2Step-4 : Add up the first 2 terms, pulling out like factors :

                    x • (x+1)

              Add up the last 2 terms, pulling out common factors :

                    2 • (x+1)

Step-5 : Add up the four terms of step 4 :

                    (x+2)  •  (x+1)


             Which is the desired factorization

Final result :

(x + 2) • (x + 1) • (x + 3) • (x - 4)