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Solution - Finding the roots of polynomials

x=2
x=2
x=2
x=-2

Step by Step Solution

Rearrange:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :

                     x^10-(1024)=0 

Step by step solution :

Step  1  :

Trying to factor as a Difference of Squares :

 1.1      Factoring:  x10-1024 

Theory : A difference of two perfect squares,  A2 - B2  can be factored into  (A+B) • (A-B)

Proof :  (A+B) • (A-B) =
         A2 - AB + BA - B2 =
         A2 - AB + AB - B2 =
         A2 - B2

Note :  AB = BA is the commutative property of multiplication.

Note :  - AB + AB equals zero and is therefore eliminated from the expression.

Check : 1024 is the square of 32
Check :  x10  is the square of  x5 

Factorization is :       (x5 + 32)  •  (x5 - 32) 

Polynomial Roots Calculator :

 1.2    Find roots (zeroes) of :       F(x) = x5 + 32
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  32.

 
The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant :  1 ,2 ,4 ,8 ,16 ,32

 
Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      31.00   
     -2     1      -2.00      0.00    x + 2 
     -4     1      -4.00      -992.00   
     -8     1      -8.00     -32736.00   
     -16     1     -16.00     -1048544.00   
     -32     1     -32.00     -33554400.00   
     1     1      1.00      33.00   
     2     1      2.00      64.00   
     4     1      4.00      1056.00   
     8     1      8.00     32800.00   
     16     1      16.00     1048608.00   
     32     1      32.00     33554464.00   


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
   x5 + 32 
can be divided with  x + 2 

Polynomial Long Division :

 1.3    Polynomial Long Division
Dividing :  x5 + 32 
                              ("Dividend")
By         :    x + 2    ("Divisor")

dividend  x5         + 32 
- divisor * x4   x5 + 2x4         
remainder  - 2x4       + 32 
- divisor * -2x3   - 2x4 - 4x3       
remainder      4x3     + 32 
- divisor * 4x2       4x3 + 8x2     
remainder      - 8x2   + 32 
- divisor * -8x1       - 8x2 - 16x   
remainder          16x + 32 
- divisor * 16x0           16x + 32 
remainder           0

Quotient :  x4-2x3+4x2-8x+16  Remainder:  0 

Polynomial Roots Calculator :

 1.4    Find roots (zeroes) of :       F(x) = x4-2x3+4x2-8x+16

     See theory in step 1.2
In this case, the Leading Coefficient is  1  and the Trailing Constant is  16.

 
The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant :  1 ,2 ,4 ,8 ,16

 
Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      31.00   
     -2     1      -2.00      80.00   
     -4     1      -4.00      496.00   
     -8     1      -8.00      5456.00   
     -16     1     -16.00     74896.00   
     1     1      1.00      11.00   
     2     1      2.00      16.00   
     4     1      4.00      176.00   
     8     1      8.00      3280.00   
     16     1      16.00     58256.00   


Polynomial Roots Calculator found no rational roots

Polynomial Roots Calculator :

 1.5    Find roots (zeroes) of :       F(x) = x5-32

     See theory in step 1.2
In this case, the Leading Coefficient is  1  and the Trailing Constant is  -32.

 
The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant :  1 ,2 ,4 ,8 ,16 ,32

 
Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      -33.00   
     -2     1      -2.00      -64.00   
     -4     1      -4.00     -1056.00   
     -8     1      -8.00     -32800.00   
     -16     1     -16.00     -1048608.00   
     -32     1     -32.00     -33554464.00   
     1     1      1.00      -31.00   
     2     1      2.00      0.00    x-2 
     4     1      4.00      992.00   
     8     1      8.00     32736.00   
     16     1      16.00     1048544.00   
     32     1      32.00     33554400.00   


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
   x5-32 
can be divided with  x-2 

Polynomial Long Division :

 1.6    Polynomial Long Division
Dividing :  x5-32 
                              ("Dividend")
By         :    x-2    ("Divisor")

dividend  x5         - 32 
- divisor * x4   x5 - 2x4         
remainder    2x4       - 32 
- divisor * 2x3     2x4 - 4x3       
remainder      4x3     - 32 
- divisor * 4x2       4x3 - 8x2     
remainder        8x2   - 32 
- divisor * 8x1         8x2 - 16x   
remainder          16x - 32 
- divisor * 16x0           16x - 32 
remainder           0

Quotient :  x4+2x3+4x2+8x+16  Remainder:  0 

Polynomial Roots Calculator :

 1.7    Find roots (zeroes) of :       F(x) = x4+2x3+4x2+8x+16

     See theory in step 1.2
In this case, the Leading Coefficient is  1  and the Trailing Constant is  16.

 
The factor(s) are:

of the Leading Coefficient :  1
 
of the Trailing Constant :  1 ,2 ,4 ,8 ,16

 
Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      11.00   
     -2     1      -2.00      16.00   
     -4     1      -4.00      176.00   
     -8     1      -8.00      3280.00   
     -16     1     -16.00     58256.00   
     1     1      1.00      31.00   
     2     1      2.00      80.00   
     4     1      4.00      496.00   
     8     1      8.00      5456.00   
     16     1      16.00     74896.00   


Polynomial Roots Calculator found no rational roots

Equation at the end of step  1  :

  (x4-2x3+4x2-8x+16)•(x+2)•(x4+2x3+4x2+8x+16)•(x-2)  = 0 

Step  2  :

Theory - Roots of a product :

 2.1    A product of several terms equals zero. 

 
When a product of two or more terms equals zero, then at least one of the terms must be zero. 

 
We shall now solve each term = 0 separately 

 
In other words, we are going to solve as many equations as there are terms in the product 

 
Any solution of term = 0 solves product = 0 as well.

Quartic Equations :

 2.2     Solve   x4-2x3+4x2-8x+16 = 0

In search of an interavl at which the above polynomial changes sign, from negative to positive or the other wayaround.

Method of search: Calculate polynomial values for all integer points between x=-20 and x=+20

No interval at which a change of sign occures has been found. Consequently, Bisection Approximation can not be used. As this is a polynomial of an even degree it may not even have any real (as opposed to imaginary) roots

Solving a Single Variable Equation :

 2.3      Solve  :    x+2 = 0 

 
Subtract  2  from both sides of the equation : 
 
                     x = -2

Quartic Equations :

 2.4     Solve   x4+2x3+4x2+8x+16 = 0

In search of an interavl at which the above polynomial changes sign, from negative to positive or the other wayaround.

Method of search: Calculate polynomial values for all integer points between x=-20 and x=+20

No interval at which a change of sign occures has been found. Consequently, Bisection Approximation can not be used. As this is a polynomial of an even degree it may not even have any real (as opposed to imaginary) roots

Solving a Single Variable Equation :

 2.5      Solve  :    x-2 = 0 

 
Add  2  to both sides of the equation : 
 
                     x = 2

Two solutions were found :

  1.  x = 2
  2.  x = -2

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