Last visit was: 15 Sep 2026, 09:25 It is currently 15 Sep 2026, 09:25
Home
Messages
Tests
Schools
Events
Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
605-655 (Medium)|   Algebra|      
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,057
Own Kudos:
20,419
 [53]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,057
Kudos: 20,419
 [53]
Which of the following is the closest value of x such that 07 Jun 2017, 01:23
2
Kudos
Add Kudos
51
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

45% (medium)

Question Stats:

65% (01:51) correct 35% (02:11) wrong based on 607 sessions

History

Date
Time
Result
Not Attempted Yet
Which of the following is the closest value of x such that \(x^{20}+x^2+0.0000019=0.09\)?

A. 0.1
B. 0.01
C. 0.3
D. 0.03
E. 0.003
ShowHide Answer
Official Answer
C
Most Helpful Reply
User avatar
BrentGMATPrepNow
User avatar
Major Poster
Joined: 12 Sep 2015
Last visit: 31 Oct 2025
Posts: 6,727
Own Kudos:
37,326
 [18]
Given Kudos: 799
Location: Canada
Expert
Expert reply
Posts: 6,727
Kudos: 37,326
 [18]
Which of the following is the closest value of x such that 07 Jun 2017, 08:12
12
Kudos
Add Kudos
6
Bookmarks
Bookmark this Post
MathRevolution
Which of the following is the closest value of x such that \(x^{20}+x^2+0.0000019=0.09\)?

A. 0.1
B. 0.01
C. 0.3
D. 0.03
E. 0.003
Show more

When a GMAT question tells us to find the "closest value" or the "approximate value," this usually gives us the go ahead to estimate.

First recognize that, for all 5 answer choices, the value of x^20 becomes inconsequential
For example, if x = 0.1, then x^20 = (0.1)^20 = (1/10)^20 = 1/100000000000000000000
The same applies to all 5 answer choices.

Since the value of x^20 has almost no effect on the equation, we can safely ignore it.

Likewise, the value 0.0000019 is very very very small in relation to 0.09
So, we can safely ignore it.

So, our equation becomes x² ≈ 0.09
Solve to get: x ≈ 0.3

Answer:
Show Spoiler
C

Cheers,
Brent
User avatar
elegantm
User avatar
Joined: 28 May 2017
Last visit: 11 Sep 2018
Posts: 223
Own Kudos:
747
 [6]
Given Kudos: 12
Concentration: Finance, General Management
Posts: 223
Kudos: 747
 [6]
Which of the following is the closest value of x such that 07 Jun 2017, 01:36
4
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
MathRevolution
Which of the following is the closest value of x such that \(x^{20}+x^2+0.0000019=0.09\)?
A. 0.1
B. 0.01
C. 0.3
D. 0.03
E. 0.003
Show more

\(x^{20}+x^2+0.0000019=0.09\)

Nice Question
Rather than testing options, one of the best way to solve the solve is to reduce the variables
\(x^{20}+x^2+0.0000019=0.09\)
Reduced to
\(x^2+0.0000019=0.09\)
Reduced to
\(x^2=0.09\)

Voila, x = 0.3

Answer C
General Discussion
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,057
Own Kudos:
20,419
 [3]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,057
Kudos: 20,419
 [3]
Which of the following is the closest value of x such that 09 Jun 2017, 02:35
1
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
==> From \(x^{20}+x^2+0.0000019=0.09, x^{20}\) and 0.0000019 are very close to 0, so you can ignore them, and the equation becomes \(x^2=0.09=0.3^2\). Thus, you get x=0.3.

The answer is C.
Answer: C
User avatar
arvind910619
User avatar
Joined: 20 Dec 2015
Last visit: 18 Oct 2024
Posts: 800
Own Kudos:
620
Given Kudos: 755
Status:Learning
Location: India
Concentration: Operations, Marketing
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
GPA: 3.4
WE:Engineering (Manufacturing)
Products:
My Reviews
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
Posts: 800
Kudos: 620
Which of the following is the closest value of x such that 09 Jun 2017, 08:41
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Imo C we can do this question by approximations
Ignore x^20 and 0.0000019
Thus we have
X^2 =0.09
0.3 is our answer

Sent from my ONE E1003 using GMAT Club Forum mobile app
User avatar
energetics
User avatar
Joined: 05 Feb 2018
Last visit: 09 Oct 2020
Posts: 292
Own Kudos:
987
 [1]
Given Kudos: 325
Posts: 292
Kudos: 987
 [1]
Which of the following is the closest value of x such that 10 Mar 2019, 10:55
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
This question can be solved by looking at the answer choices and applying logic. Since every time we square a decimal we reduce it's value (i.e. the number of 0s between the decimal point and the number increases), the closest answer would be the the one that has the closest number after being squared, which is C.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 39,228
Own Kudos:
1,159
Posts: 39,228
Kudos: 1,159
Which of the following is the closest value of x such that 02 May 2025, 23:19
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderator:
Bunuel
Math Expert
113537 posts