See the attached file
how do you answer it?

 3.1     Pull out like factors :

   3x2 - 147  =   3 • (x2 - 49) 

 3.2      Factoring:  x2 - 49 

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 :  x2  is the square of  x1 

Factorization is :       (x + 7)  •  (x - 7) 

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