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Solution - Simplification or other simple results

2x315
2x^3-15

Step by Step Solution

Step  1  :

Equation at the end of step  1  :

  (2x2 • x) -  15

Step  2  :

Trying to factor as a Difference of Cubes:

 2.1      Factoring:  2x3-15 

Theory : A difference of two perfect cubes,  a3 - b3 can be factored into
              (a-b) • (a2 +ab +b2)

Proof :  (a-b)•(a2+ab+b2) =
            a3+a2b+ab2-ba2-b2a-b3 =
            a3+(a2b-ba2)+(ab2-b2a)-b3 =
            a3+0+0-b3 =
            a3-b3


Check :  2  is not a cube !!

Ruling : Binomial can not be factored as the difference of two perfect cubes

Polynomial Roots Calculator :

 2.2    Find roots (zeroes) of :       F(x) = 2x3-15
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  2  and the Trailing Constant is  -15.

 
The factor(s) are:

of the Leading Coefficient :  1,2
 
of the Trailing Constant :  1 ,3 ,5 ,15

 
Let us test ....

  P  Q  P/Q  F(P/Q)   Divisor
     -1     1      -1.00      -17.00   
     -1     2      -0.50      -15.25   
     -3     1      -3.00      -69.00   
     -3     2      -1.50      -21.75   
     -5     1      -5.00      -265.00   
     -5     2      -2.50      -46.25   
     -15     1     -15.00     -6765.00   
     -15     2      -7.50      -858.75   
     1     1      1.00      -13.00   
     1     2      0.50      -14.75   
     3     1      3.00      39.00   
     3     2      1.50      -8.25   
     5     1      5.00      235.00   
     5     2      2.50      16.25   
     15     1      15.00      6735.00   
     15     2      7.50      828.75   


Polynomial Roots Calculator found no rational roots

Final result :

  2x3 - 15

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