Solution - Linear equations with one unknown

Rearrange:

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

                     805-(5*x^3)=0 

Step by step solution :

Step  1  :

Equation at the end of step  1  :

  805 -  5x3  = 0 

Step  2  :

Step  3  :

Pulling out like terms :

 3.1     Pull out like factors :

   805 - 5x³  =   -5 • (x³ - 161) 

Trying to factor as a Difference of Cubes:

 3.2      Factoring:  x³ - 161 

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 :  161  is not a cube !!
Ruling : Binomial can not be factored as the difference of two perfect cubes

Polynomial Roots Calculator :

 3.3    Find roots (zeroes) of :       F(x) = x³ - 161
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  -161.

 The factor(s) are:

of the Leading Coefficient :  1
 of the Trailing Constant :  1 ,7 ,23 ,161

 Let us test ....

Polynomial Roots Calculator found no rational roots

Equation at the end of step  3  :

  -5 • (x3 - 161)  = 0 

Step  4  :

Equations which are never true :

 4.1      Solve :    -5   =  0

This equation has no solution.
A a non-zero constant never equals zero.

Solving a Single Variable Equation :

 4.2      Solve  :    x³-161 = 0 

 Add  161  to both sides of the equation : 
                      x³ = 161
When two things are equal, their cube roots are equal. Taking the cube root of the two sides of the equation we get:  
                      x  =  ∛ 161  

 The equation has one real solution
This solution is  x = ∛161 = 5.4401

One solution was found :