SATpreparation.net

Basic Equations - Difficult (for scores form 600 to 800)
    STRATEGY:  Read the question two or three times to be 
                          sure you understand what it says.  

Solve:
    STRATEGY:  Write all the steps to avoid careless errors.
                                
                 (a + b) (a - b)  =  99   

      If  (a + b)  =  11, substitute  11  for  (a + b): 
                                
                     11   (a - b)  =  99
    
                            (a - b)  =   9 
                                                                                                                      
Answer:

      STRATEGY:  Read the question again to be sure you know what it asks.

      If  (a + b) = 11  and  (a - b) = 9, solve for x using simultaneous equations: 
                                
                 (a + b)  =  11   
                                
              +  (a - b)  =   9   
              ________________
                                
                      2a   =   20

                       a   =    10             
                       

Click here to return to Basic Equations.

The text is created by College Admissions Services.  Copyright 2007.  All rights reserved.
             SAT is a registered trademark of the College Entrance Examination Board,
   which is not affiliated with the production of these materials nor does it endorse them.