Question

Which are the solutions of the quadratic equation x2 =-5-3

Answer 1

Answer: x = 2 • ± √2 = ± 2.8284

Step-by-step explanation:

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 : 8 is not a square !!  

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

Equation at the end of step  1  :

 x2 - 8  = 0  

Step  2  :

Solving a Single Variable Equation :

2.1      Solve  :    x2-8 = 0  

Add  8  to both sides of the equation :  

                     x2 = 8  

 

When two things are equal, their square roots are equal. Taking the square root of the two sides of the equation we get:  

                     x  =  ± √ 8  

Can  √ 8 be simplified ?

Yes!   The prime factorization of  8   is

  2•2•2  

To be able to remove something from under the radical, there have to be  2  instances of it (because we are taking a square i.e. second root).

√ 8   =  √ 2•2•2   =

               ±  2 • √ 2  

The equation has two real solutions  

These solutions are  x = 2 • ± √2 = ± 2.8284  

 

Two solutions were found :

                  x = 2 • ± √2 = ± 2.8284

Not sure what you need help with, but I hope I helped you somehow.