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Algebra - OG-2nd Edition

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Algebra - OG-2nd Edition

by shanice » Thu Jul 12, 2012 8:43 am
What is the value of a-b?

(1)a=b+4
(2)(a-b)^2 = 16

Answer is A.

My workings:-

Statement 1 = a-b = 4 (Sufficient)
Statement 2 - a-b = square root 16. Since it is a square root, the answer should always be positive
So, the answer is 4 (sufficient). Unfortunately, the answer in the book for
statement 2 is insufficient.According to the book, the answer is 4 or -4 but as I
we can only get such 4 or -4 if it's an exponent, right?

Can someone please explain to me why my understanding for statement 2 is wrong?
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Source: — Data Sufficiency |
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by niketdoshi123 » Thu Jul 12, 2012 9:37 am
shanice wrote: Statement 2 - a-b = square root 16. Since it is a square root, the answer should always be positive
So, the answer is 4 (sufficient).

Can someone please explain to me why my understanding for statement 2 is wrong?
Its the square of any number that has to be positive not the square root, which can be both positive or negative.

Since (4)^2 = 16 and (-4)^2 = 16 , therefore the square root of (16) can be 4 or -4.
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by eagleeye » Thu Jul 12, 2012 10:22 am
shanice wrote:What is the value of a-b?

(1)a=b+4
(2)(a-b)^2 = 16

Answer is A.

My workings:-

Statement 1 = a-b = 4 (Sufficient)
Statement 2 - a-b = square root 16. Since it is a square root, the answer should always be positive
So, the answer is 4 (sufficient). Unfortunately, the answer in the book for
statement 2 is insufficient.According to the book, the answer is 4 or -4 but as I
we can only get such 4 or -4 if it's an exponent, right?

Can someone please explain to me why my understanding for statement 2 is wrong?
shanice:

Please read this article I wrote for the same issue. It may help :)
https://www.beatthegmat.com/squares-squa ... tml#476551
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