Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 47168

If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
25 Nov 2014, 08:15
Question Stats:
88% (00:55) correct 12% (01:23) wrong based on 147 sessions
HideShow timer Statistics



Manager
Joined: 12 Aug 2014
Posts: 151
Location: United States (AZ)
Concentration: Finance, Strategy

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
25 Nov 2014, 08:23
If (x + 2)^2 = − 4 + 10x , then which of the following could be the value of x?
Factor out: x^2 + 4x + 4 = 4 + 10x Simplify: x^2  6x + 8 = 0 Find roots: (x  4)(x  2) = 0
Therefore, x = 4 or x = 2 are solutions to the equation. Of the two, only x = 2 is available as answer choice A.



Intern
Joined: 25 May 2014
Posts: 46

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
25 Nov 2014, 10:13
Check with plugging values for x= 2 LHS = RHS (2 + 2)^2 = − 4 + 10*2 [A]
_________________
Never Try Quitting, Never Quit Trying



SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1837
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
25 Nov 2014, 18:42
Answer = A) 2 \(x^2 + 4x + 4 = 4 + 10x\) \(x^2  6x + 8 = 0\) (x  4)(x  2) = 0 x = 4 OR x = 2
_________________
Kindly press "+1 Kudos" to appreciate



Current Student
Joined: 02 Sep 2014
Posts: 89
Location: United States
GPA: 3.97

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
26 Nov 2014, 01:17
Bunuel wrote: If (x + 2)^2 = − 4 + 10x , then which of the following could be the value of x?
A) 2 B) 1 C) 0 D) −1 E) −2
Kudos for a correct solution.
Source: Chili Hot GMAT Solve equation to get x^26x+8 = 0 which has solutions x=4 or x=2. Answer is A.



Math Expert
Joined: 02 Sep 2009
Posts: 47168

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
26 Nov 2014, 07:17
Bunuel wrote: If (x + 2)^2 = − 4 + 10x , then which of the following could be the value of x?
A) 2 B) 1 C) 0 D) −1 E) −2
Kudos for a correct solution.
Source: Chili Hot GMAT BacksolvingThe key to using backsolving is to use the answer choices and see if they work. In this respect, backsolving is like picking numbers except that the numbers we pick are one or more of the actual answer choices. Look for the answer which makes both sides equal. In this particular problem, we may choose to start testing on any single answer choice. Choice A is as good a starting point as any. Choice A. (2 + 2)2 = −4 + 10(2) 16 = 16; This is the correct answer since both sides are equal. Choice B. (1 + 2)2 = −4 + 10(1); 9 = 6. This is a wrong answer since both sides are not equal. Choice C. (0 + 2)2 = −4 + 10(0); 4 = −4. This is a wrong answer since both sides are not equal. Choice D. (−1 + 2)2 = −4 + 10(−1); 1 = −14. This is a wrong answer since both sides are not equal. Choice E. (−2 + 2)2 = −4 + 10(−2); 0 = −24. This is a wrong answer since both sides are not equal. Answer: A.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 12 Sep 2014
Posts: 161
Concentration: Strategy, Leadership
GPA: 3.94

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
26 Nov 2014, 11:34
Simply expand (x+2)^2 and combine all terms on one side of the equation: x^2 + 4x + 4 = 4 + 10x, yielding x^2 6x + 8=0. The two solutions are 2 and 4.
Choice A



Target Test Prep Representative
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2679

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
29 Oct 2017, 07:20
Bunuel wrote: If (x + 2)^2 = − 4 + 10x , then which of the following could be the value of x?
A) 2 B) 1 C) 0 D) −1 E) −2 We can simplify the given equation and factor the result: x^2 + 4x + 4 = 4 + 10x x^2  6x + 8 = 0 (x  4)(x  2) = 0 x = 4 or x = 2 Alternate Solution: Let’s substitute each value in the answer choices for x until we find a value that satisfies the given equation: A) x = 2 Is (2 + 2)^2 = 4 + 10(2) ? Is 4^2 = 4 + 20 ? Is 16 = 16? Yes. Answer: A
_________________
Jeffery Miller
Head of GMAT Instruction
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3654
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
29 Oct 2017, 07:37
Bunuel wrote: If (x + 2)^2 = − 4 + 10x , then which of the following could be the value of x?
A) 2 B) 1 C) 0 D) −1 E) −2
Kudos for a correct solution.
Source: Chili Hot GMAT \(x^2 + 4 + 4x = 4 + 10x\) Or, \(x^2 6x + 8 = 0\) Or, \(x^2 4x 2x + 8 = 0\) Or, \(x(x4) 2(x4) = 0\) Or, \((x2)(x4) = 0\) So, \(x = 2\) or \(x = 4\) Among the given options, only(A) satisfies, hence, correct answer must be (A)
_________________
Thanks and Regards
Abhishek....
PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS
How to use Search Function in GMAT Club  Rules for Posting in QA forum  Writing Mathematical Formulas Rules for Posting in VA forum  Request Expert's Reply ( VA Forum Only )



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12007
Location: United States (CA)

Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va
[#permalink]
Show Tags
25 Nov 2017, 15:07
Hi All, While this question can be solved Algebraically, we're told that one of the numbers IS a solution to the equation  so we can also solve it by TESTing THE ANSWERS. Once we find an answer that 'fits', we can stop working. Let's start with Answer A: 2... IF X=2, then we have (4)^2 = 4 +2(10).... 16 = 16. Since the equation 'balances', this must the answer. Final Answer: GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************




Re: If (x + 2)^2 = − 4 + 10x , then which of the following could be the va &nbs
[#permalink]
25 Nov 2017, 15:07






