Solution - Nonlinear equations

Rearrange:

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

                     2*x^2+4*x^2-(42)=0 

Step by step solution :

Step  1  :

Equation at the end of step  1  :

  ((2 • (x2)) +  22x2) -  42  = 0 
 Step  2  :

Equation at the end of step  2  :

  (2x2 +  22x2) -  42  = 0 

Step  3  :

Step  4  :

Pulling out like terms :

 4.1     Pull out like factors :

   6x² - 42  =   6 • (x² - 7) 

Trying to factor as a Difference of Squares :

 4.2      Factoring:  x² - 7 

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 : 7 is not a square !!

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

Equation at the end of step  4  :

  6 • (x2 - 7)  = 0 

Step  5  :

Equations which are never true :

 5.1      Solve :    6   =  0

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

Solving a Single Variable Equation :

 5.2      Solve  :    x²-7 = 0 

 Add  7  to both sides of the equation : 
                      x² = 7
 
 When two things are equal, their square roots are equal. Taking the square root of the two sides of the equation we get:  
                      x  =  ± √ 7  

 The equation has two real solutions  
 These solutions are  x = ± √7 = ± 2.6458  
 

Two solutions were found :