Gruber's Shortest SAT Test Answer Guide
Article Index
Gruber's Shortest SAT Test Answer Guide
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19

2.Where a ≠ 1, (a7 - a6) / (a - 1) =

A) a/(a -1)
B) 1/(a - 1)
C) a6 - a5
D) a5
E) a6

(A) Did you think that a7 - a6= a1 = a? Know your math rules. Choice E is correct.

Here's the best way:
Use Strategies 4 and 12, p. 81 and 98; BASIC SKILL - Mini Math Refresher - Algebra, p. 156; Math Refresher (429), p. 257:
When dealing with complicated quantities or equations, it is sometimes simpler to factor to see the quantity take a different form. Factor out a6 from the quantity a7 - a6. You get a6 (a - 1). Thus

a7 – a6 = a6 (a - 1) = a6
-----------    ------------
   a - 1          a - 1 

(B) Did you think that a7 - a6 = 1. Know your math rules. Choice E is correct. Here's the best way:
Use Strategies 4 and 12, p. 81 and 98; BASIC SKILL - Mini Math Refresher - Algebra, p. 156; Math Refresher (429), p. 257:
When dealing with complicated quantities or equations, it is sometimes simpler to factor to see the quantity take a different form. Factor out a6 from the quantity a7 - a6. You get a6 (a - 1). Thus

a7 - a6 = a6 (a - 1) = a6
----------    -------------  
  a - 1        a - 1 

(C) Did you think that

a7 - a6
-----------
 a – 1
would reduce the exponents and you would get a6 - a5?

Know your math rules. Choice E is correct Here's the best way:
Use Strategies 4 and 12, p. 81 and 98; BASIC SKILL - Mini Math Refresher - Algebra, p. 156; Math Refresher (429), p. 257: When dealing with complicated quantities or equations, it is sometimes simpler to factor to see the quantity take a different form. Factor out a6 from the quantity a7 – a6. You get a6 (a - 1). Thus

a7 - a6 = a6 (a - 1) = a6
-----------    -------------  
  a – 1        a – 1 


(D) Know your math rules! Choice E is correct. Here's the best way:
Use Strategies 4 and 12, p. 81 and 98; BASIC SKILL - Mini Math Refresher - Algebra, p. 156; Math Refresher (429), p. 257: When dealing with complicated quantities or equations, it is sometimes simpler to factor to see the quantity take a different form. Factor out a6 from the quantity a7 – a6. You get a6 (a - 1). Thus

a7 - a6 = a6 (a - 1) = a6
-----------    -------------
   a – 1        a – 1 

(E) You are right! Choice E is correct. And here's the best way:
Use Strategies 4 and 12, p. 81 and 98; BASIC SKILL - Mini Math Refresher - Algebra, p. 156; Math Refresher (429), p. 257: When dealing with complicated quantities or equations, it is sometimes simpler to factor to see the quantity take a different form. Factor out a6 from the quantity a7 – a6. You get a6 (a - 1). Thus

a7 – a6 = a6 (a – 1) = a6
-----------   -------------- 
  a – 1        a – 1