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17 Jun 2018, 06:37
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B
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Difficulty:
15%
(low)
Question Stats:
76% (00:57) correct
24%
(01:07)
wrong
based on 630
sessions
History
Date
Time
Result
Not Attempted Yet
What is the value of \(\frac{3^{-(x + y)}}{3^{-(x - y)}}\)?
(1) x = 2
(2) y = 3
(1) x = 2
(2) y = 3
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17 Jun 2018, 06:47
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\(\frac{3^{-(x + y)}}{3^{-(x - y)}}\)= \(3^{-(x + y)+(x - y)}\)=\(3^{-x+y+x-y}\)=\(3^{-2y}\). So the value will depend on the value of \(y\) only.
(1) x = 2. Not Sufficient
(2) y = 3. Sufficient
Answer B.
(1) x = 2. Not Sufficient
(2) y = 3. Sufficient
Answer B.
17 Jun 2018, 11:09
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Solution
To find:
• The value of the expression \(\frac{3^{-(x + y)}}{3^{-(x - y)}}\)
Approach and Working:
We can simplify the given expression as
- • \(\frac{3^{-(x + y)}}{3^{-(x - y)}}\)
= \(3^{(-x - y) – (-x + y)}\)
= \(3^{(-x - y + x - y)}\)
= \(3^{(- 2y)}\)
Therefore, if we know the value of y, we can find out the value of the expression
Analysing Statement 1
- • As per the information given in statement 1, x = 2
- o From this statement, we don’t find any information about y
Hence, statement 2 is not sufficient to answer
Analysing Statement 2
- • As per the information given in statement 2, y = 3
- o Substituting the value of y, we can find the value of the given expression
Hence, statement 2 is sufficient to answer
Hence, the correct answer is option B.
Answer: B
