 It is currently 30 Nov 2020, 03:45 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # If xy ≠ 0 and x ≠ –y  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Retired Moderator Joined: 07 Jun 2014
Posts: 4803
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 175

Kudos [?]: 3037 , given: 394

If xy ≠ 0 and x ≠ –y [#permalink]
Expert's post 00:00

Question Stats: 84% (01:05) correct 15% (02:30) wrong based on 32 sessions
If xy ≠ 0 and x ≠ –y,$$\frac{x^{36}-y^{36}}{(x^{18}+y^{18})(x^{9}+y^{9})}$$

(A) 1
(B) $$x^2 - y^2$$
(C) $$x^9 - y^9$$
(D) $$x^{18} - y^{18}$$
(E)$$\frac{1}{x^{9}-y^{9}}$$
[Reveal] Spoiler: OA

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test Moderator  Joined: 07 Jan 2018
Posts: 697
Followers: 11

Kudos [?]: 785  , given: 88

Re: If xy ≠ 0 and x ≠ –y [#permalink]
1
KUDOS
looking at the question stem. The numerator can be simplified to the form $$(x-y)(x+y)$$ because it is in the form $$x^2 - y^2$$
Hence the fraction becomes $$\frac{(x^1^8 + y^1^8)(x^1^8 - y^1^8)}{(x^1^8 + y^1^8)(x^9 + y^9)}$$
we can cancel $$(x^1^8 + y^1^8)$$ from both numerator and denominator.
Leaving $$\frac{(x^1^8 - y^1^8)}{(x^9 + y^9)}$$

numerator can again be simplified

$$\frac{(x^9 - y^9)(x^9 + y^9)}{(x^9 + y^9)}$$
we can again cancel $$(x^9 + y^9)$$
finally, leaving $$(x^9 - y^9)$$
_________________

Need Practice? 20 Free GRE Quant Tests available for free with 20 Kudos Re: If xy ≠ 0 and x ≠ –y   [#permalink] 23 Jul 2018, 08:06
Display posts from previous: Sort by

# If xy ≠ 0 and x ≠ –y  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.