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Thu Mar 18, 2021 12:30 am
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
69% (01:16) correct
31%
(01:19)
wrong
based on 113
sessions
History
Date
Time
Result
Not Attempted Yet
If a^2 = b^2 = 25, what is the value of a + b?
(1) a - b = 0
(2) ab = 25
(1) a - b = 0
(2) ab = 25
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
Thu Mar 18, 2021 1:08 am
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Bunuel
Given, \(a^2 = b^2 = 25\)
i.e. a = +5 or -5 also, b = +5 or -5
Question: a + b = ?
Statement 1: a - b = 0
i.e. a = b
Case 1: a = b = 5, then a+b = 10
Case 2: a = b = -5, then a+b = -10
NOT SUFFICIENT
Statement 2: ab = 25
i.e. signs of a and b are identical
Case 1: a = b = 5, then a+b = 10
Case 2: a = b = -5, then a+b = -10
NOT SUFFICIENT
Combining,
Case 1: a = b = 5, then a+b = 10
Case 2: a = b = -5, then a+b = -10
NOT SUFFICIENT
Answer: Option E
mohammadfaraaz123
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Thu Mar 18, 2021 4:33 am
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a^2 = b^2 =25
a = 5 or -5
b=5 or -5
Statement (1): a - b = 0
a=b
Case 1: a = b= 5
5-5=0.
Hence 5=5 = 10
Case 2: a = b = -5
-5 -( -5) = -5 + 5 = 0.
Hence, a+b = -5 + (-5) = -10
Insufficient.
Statement (2): ab = 25
Implies both a and b have identical signs.
Possible values:
a= 5 or -5
b = 5 or -5
For positive signs : a+b = 10
For negative signs: a+b = -10
Insufficient.
On combining too we are unable to narrow down to specific signs of 'a' and 'b'.
Hence, the answer should be E.
a = 5 or -5
b=5 or -5
Statement (1): a - b = 0
a=b
Case 1: a = b= 5
5-5=0.
Hence 5=5 = 10
Case 2: a = b = -5
-5 -( -5) = -5 + 5 = 0.
Hence, a+b = -5 + (-5) = -10
Insufficient.
Statement (2): ab = 25
Implies both a and b have identical signs.
Possible values:
a= 5 or -5
b = 5 or -5
For positive signs : a+b = 10
For negative signs: a+b = -10
Insufficient.
On combining too we are unable to narrow down to specific signs of 'a' and 'b'.
Hence, the answer should be E.
