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 Post subject: GMAT Symbols
PostPosted: Mon Jan 30, 2012 6:00 pm 
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Let a be a positive integer. Let n # a equal n²ª if a is odd and n³ª if a is even. Then (2 # 3) + (3 # 2) – (3 # 3) is equal to
A. 64
B. 82
C. 128
D. 512
E. 1522

(A) Let's calculate expressions within brackets first.

(2 # 3) corresponds to (n # a), where n = 2, a = 3. Since 3 is odd, then the we use formula n²ª to calculate the result. It equals 2 to the (2 × 3)-th power, which can be calculated as (2³)² = 8² = 64.

(3 # 2) corresponds to (n # a), where n = 3, a = 2. Since 2 is even, then the we use formula n³ª to calculate the result. It equals 3 to the (3 × 2)-th power, which can be calculated as (3²)³ = 9³ = 81 × 9 = 729.

(3 # 3) corresponds to (n # a), where n = 3, a = 3. Since 3 is odd, then the we use formula n²ª to calculate the result. It equals 3 to the (2 × 3)-th power, which can be calculated as (3²)³ = 9³ = 81 × 9 = 729.

Therefore
(2 # 3) + (3 # 2) – (3 # 3) = 64 + 729 – 729 = 64.


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