It is currently 19 Sep 2017, 05:09

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is a=b?

Author Message
TAGS:

Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 3985

Kudos [?]: 2696 [0], given: 0

GPA: 3.82

Show Tags

11 Jul 2016, 00:50
Expert's post
1
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

82% (00:27) correct 18% (00:31) wrong based on 67 sessions

HideShow timer Statistics

Is a=b?
1) a^2=b^2
2) a=1

*An answer will be posted in 2 days
[Reveal] Spoiler: OA

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Kudos [?]: 2696 [0], given: 0

Director
Joined: 26 Nov 2012
Posts: 581

Kudos [?]: 157 [0], given: 45

Show Tags

11 Jul 2016, 03:10
MathRevolution wrote:
Is a=b?
1) a^2=b^2
2) a=1

*An answer will be posted in 2 days

Given to find if a=b?

Stat 1 : $$a^2$$ = $$b^2$$.

Here a or b can be positive or negative, when we square negative or positive we get the same result.

For ex:
if a = -2 or b = 2. Upon squaring we get both same result i.e. 4. But a is -2 , b is +2. Here a is not equal to b.

if a = 2 or b = 2. Upon squaring we get both same result i.e. 4. But a is +2 , b is +2. Here a = b .

Two different cases. Insufficient.

Stat 2 : Given only about a = 1, but we are not sure about the value of b if it a positive or negative or what it is. Insufficient.

Stat 1 + Stat 2 : If a = 1 ( from stat 2).
Substitute in Stat 1 => 1 = $$b^2$$. Now here b will get 1 or -1. There is no unique value. Thus both stats insufficient.

Correct option is E.

Kudos [?]: 157 [0], given: 45

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 3985

Kudos [?]: 2696 [0], given: 0

GPA: 3.82

Show Tags

11 Jul 2016, 18:24
There are 2 variables in the original condition. In order to match the number of variables and the number of equations, we need 2 equations. There is a high chance that C is the correct answer. Using 1) & 2), from a=1 and b=-1, 1, the answer is both yes or no. Hence, the conditions are not sufficient and the correct answer is E.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Kudos [?]: 2696 [0], given: 0

Director
Joined: 05 Mar 2015
Posts: 964

Kudos [?]: 269 [0], given: 41

Show Tags

11 Jul 2016, 19:17
MathRevolution wrote:
Is a=b?
1) a^2=b^2
2) a=1

*An answer will be posted in 2 days

(1)
sq. root both sides then
IaI=IbI
a and b can be positive or negative having same magnitude(distance from 0)
Not suff...
(2)a=1
No info on b ..
Not suff..
Combining (1) & (2)
if a=1 then b=1 or -1
Not suff....
Ans E

Kudos [?]: 269 [0], given: 41

Senior Manager
Joined: 02 Dec 2014
Posts: 380

Kudos [?]: 87 [0], given: 349

Location: Russian Federation
Concentration: General Management, Economics
GMAT 1: 640 Q44 V33
WE: Sales (Telecommunications)

Show Tags

04 Sep 2016, 02:35
Please move this question to DS section
_________________

"Are you gangsters?" - "No we are Russians!"

Kudos [?]: 87 [0], given: 349

Manager
Joined: 12 Jun 2016
Posts: 186

Kudos [?]: 27 [0], given: 108

Location: India
WE: Sales (Telecommunications)

Show Tags

03 Aug 2017, 10:05
Needed : Is $$a = b?$$

S1: $$a^2 = b^2$$

=> $$a^2 - b^2 = 0$$

=> $$(a-b)(a+b) = 0$$

=> $$a = b$$ or $$a=-b$$

Insuff

S2: $$a = 1$$. No information on b. Clearly insuff

S1+S2: $$1^2 = b^2$$

if $$b = 1$$, $$a = b$$ IF $$b=-1$$, $$a ≠ b$$

Both statements together insuff. Final answer E
_________________

My Best is yet to come!

Kudos [?]: 27 [0], given: 108

Re: Is a=b?   [#permalink] 03 Aug 2017, 10:05
Similar topics Replies Last post
Similar
Topics:
57 If ab ≠ 0, is |a-b| > |a+b|? 27 03 Aug 2017, 11:29
102 If ab ≠ 0, is ab > a/b ? 25 02 Feb 2017, 17:49
1 Is ab < 1/ab ? 2 05 May 2017, 00:35
18 Is |ab| > -ab? 14 11 Apr 2017, 08:00
6 Is 2ab > ab ? 2 24 Feb 2016, 20:52
Display posts from previous: Sort by