Solution - Factoring binomials using the difference of squares

Rearrange:

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

                     81*z^2-(4)=0 

Step by step solution :

Step  1  :

Equation at the end of step  1  :

  34z2 -  4  = 0 

Step  2  :

Trying to factor as a Difference of Squares :

 2.1      Factoring:  81z²-4 

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 :  81  is the square of  9 
Check : 4 is the square of 2
Check :  z²  is the square of  z¹ 

Factorization is :       (9z + 2)  •  (9z - 2) 

Equation at the end of step  2  :

  (9z + 2) • (9z - 2)  = 0 

Step  3  :

Theory - Roots of a product :

 3.1    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.

Solving a Single Variable Equation :

 3.2      Solve  :    9z+2 = 0 

 Subtract  2  from both sides of the equation : 
                      9z = -2
Divide both sides of the equation by 9:
                     z = -2/9 = -0.222

Solving a Single Variable Equation :

 3.3      Solve  :    9z-2 = 0 

 Add  2  to both sides of the equation : 
                      9z = 2
Divide both sides of the equation by 9:
                     z = 2/9 = 0.222

Two solutions were found :

1.  z = 2/9 = 0.222
   
2.  z = -2/9 = -0.222