Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2308:00 PM PDT
-09:00 PM PDT
Video explanations + diagnosis of 10 weakest areas + 150+ short videos + study plan!
Apr 2301:30 AM EDT
-02:30 AM EDT
Struggling with GMAT Verbal as a non-native speaker? Harsh improved his score from 595 to 695 in just 45 days—and scored a 99 %ile in Verbal (V88)! Learn how smart strategy, clarity, and guided prep helped him gain 100 points.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
11 Jul 2023, 07:45
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
86% (01:09) correct
14%
(01:26)
wrong
based on 80
sessions
History
Date
Time
Result
Not Attempted Yet
x is a positive integer, and the units digits of both \((x+2)^2\) and \((x-2)^2\) are 9. What is the units digit of x？
A. 1
B. 3
C. 5
D. 7
E. 9
A. 1
B. 3
C. 5
D. 7
E. 9
11 Jul 2023, 07:58
Kudos
Bookmarks
x, as a number, must be an odd number, such that the square of the next odd number after x - which is (x+2) - must be odd and end with 9
and also
such that the square of the previous odd number before x - which is (x-2) - must be odd and end with 9
The only numbers who have squares that can end in 9 -
3,7,13,17,23,27 ... (a pattern is established)
Therefore, the only odd number between each of the pair (3,7) or (7,13) are the ones that end with 5
and also
such that the square of the previous odd number before x - which is (x-2) - must be odd and end with 9
The only numbers who have squares that can end in 9 -
3,7,13,17,23,27 ... (a pattern is established)
Therefore, the only odd number between each of the pair (3,7) or (7,13) are the ones that end with 5
16 Jul 2023, 06:04
Kudos
Bookmarks
Quick approach:
The unit digit of (x + 2)^2 and (x - 2)^2 are 9. Perfect squares that end in 9 are 3^2, 7^2 (there is also 13 and 17 squared, but those x values are not within the answer choices so don't bother with those, where x would be 11 or 15)
3^2 -> x must be 1, 3^2 ends in 9, but -1^2 ≠ end in 9
7^2 -> x must be 5, 7^2 ends in 9, 3^2 ends in 9 (keep)
Answer C
The unit digit of (x + 2)^2 and (x - 2)^2 are 9. Perfect squares that end in 9 are 3^2, 7^2 (there is also 13 and 17 squared, but those x values are not within the answer choices so don't bother with those, where x would be 11 or 15)
3^2 -> x must be 1, 3^2 ends in 9, but -1^2 ≠ end in 9
7^2 -> x must be 5, 7^2 ends in 9, 3^2 ends in 9 (keep)
Answer C
