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Source: — Data Sufficiency |
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by mals24 » Wed Jan 28, 2009 6:28 am
Given: a^2 + c^2 = 202
A, B, C - Positive

What is the value of b - a - c?

1. b^2 + c^2 = 225
b^2-a^2 = 23
(b-a)*(b+a) = 23
You have many combinations which give you 23: 23*1, (23)^2*(1/23)
Plus you cant find out a unique value of C as well
Insuff

2. a^2 + b^2 = 265
Same problem as 1.

Combining 1 and 2

Add (b^2 + c^2 = 225) + (a^2 + b^2 = 265)

2b^2+a^2+c^2 = 490
a^2+c^2 = 202 (given)
2b^2 = 288
b^2 = 144
b = +/- 12
Since B is positive, B = 12

b^2 + c^2 = 225
c^2 = 81
c = 9

b^2-a^2 = 23
a^2 = 121
a = 11

Answer: C
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by 4meonly » Wed Jan 28, 2009 6:38 am
You are correct
GMAT Club's solution was complicated
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by piyush_nitt » Thu Jan 29, 2009 2:45 am
4meonly wrote:You are correct
GMAT Club's solution was complicated
You have 3 variables a,b and c , therefore you need atleast 3 equation for the solution.

hence C
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