Solution - Factoring binomials using the difference of squares

Step by step solution :

Step  1  :

Equation at the end of step  1  :

  (2•72b2) -  50  = 0 

Step  2  :

Step  3  :

Pulling out like terms :

 3.1     Pull out like factors :

   98b² - 50  =   2 • (49b² - 25) 

Trying to factor as a Difference of Squares :

 3.2      Factoring:  49b² - 25 

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 :  49  is the square of  7 
Check : 25 is the square of 5
Check :  b²  is the square of  b¹ 

Factorization is :       (7b + 5)  •  (7b - 5) 

Equation at the end of step  3  :

  2 • (7b + 5) • (7b - 5)  = 0 

Step  4  :

Theory - Roots of a product :

 4.1    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.

Equations which are never true :

 4.2      Solve :    2   =  0

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

Solving a Single Variable Equation :

 4.3      Solve  :    7b+5 = 0 

 Subtract  5  from both sides of the equation : 
                      7b = -5
Divide both sides of the equation by 7:
                     b = -5/7 = -0.714

Solving a Single Variable Equation :

 4.4      Solve  :    7b-5 = 0 

 Add  5  to both sides of the equation : 
                      7b = 5
Divide both sides of the equation by 7:
                     b = 5/7 = 0.714

Two solutions were found :

1.  b = 5/7 = 0.714
   
2.  b = -5/7 = -0.714