Solution - Simplification or other simple results

Step  1  :

Equation at the end of step  1  :

  22r2 -  25

Step  2  :

Trying to factor as a Difference of Squares :

 2.1      Factoring:  4r²-25 

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 :  4  is the square of  2 
Check : 25 is the square of 5
Check :  r²  is the square of  r¹ 

Factorization is :       (2r + 5)  •  (2r - 5) 

Final result :

  (2r + 5) • (2r - 5)