12. simplify –3√ 2 + 3√ 8 .

a. 3√ 2
b. –3√ 2
c. 0
d. 9√ 2

The answer is:  [A]:  3√ 2  .

Explanation:

 Simply:  -3√ 2  +  3√ 8 ;


Let us simplify:  3√ 8 ;

Let us simplify: 

√ 8  ;   →  √ 8  =  √ 4 * √ 2  =  2√ 2 ;

 
   →  √ 8  =  √ 4 * √ 2  = 2√ 2 ;


  →   3√ 8  =  3 * 2√ 2  = 6√ 2 ;

So, rewrite the original problem, substituting:  "6√ 2"  for "3√ 8" ;


       -3√ 2   +   3√ 8  =  


           -3√ 2  +  6√ 2  =  3√ 2 ; which is Answer choice: [A].