Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

 It is currently 18 Jul 2019, 10:30

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

If a^3 + a^2 – a – 1 = 0, then which one of the following could be the

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

Manager
Joined: 26 Dec 2018
Posts: 142
Location: India
If a^3 + a^2 – a – 1 = 0, then which one of the following could be the  [#permalink]

Show Tags

Updated on: 15 Jul 2019, 01:07
2
1
00:00

Difficulty:

5% (low)

Question Stats:

100% (00:42) correct 0% (00:00) wrong based on 21 sessions

HideShow timer Statistics

If a^3 + a^2 – a – 1 = 0, then which one of the following could be the value of a?

(A) 0
(B) 1
(C) 2
(D) 3
(E) 4

Source: Nova GMAT
Difficulty Level: 500

_________________
GOOD LUCK!

Originally posted by UB001 on 04 Jan 2019, 10:06.
Last edited by SajjadAhmad on 15 Jul 2019, 01:07, edited 2 times in total.
VP
Joined: 09 Mar 2018
Posts: 1002
Location: India
Re: If a^3 + a^2 – a – 1 = 0, then which one of the following could be the  [#permalink]

Show Tags

Updated on: 04 Jan 2019, 12:02
1
Manipulating the question to give

$$a^3 + a^2 – a – 1 = 0$$
$$a^2(a + 1) – 1(a + 1) = 0$$
$$(a^2 -1) (a + 1) = 0$$
$$a^2 = 1$$ or a = -1

So as you can see there are no -ive values present in the answer options.

Correct answer will be B.
_________________
If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Originally posted by KanishkM on 04 Jan 2019, 11:05.
Last edited by KanishkM on 04 Jan 2019, 12:02, edited 1 time in total.
GMATH Teacher
Status: GMATH founder
Joined: 12 Oct 2010
Posts: 937
Re: If a^3 + a^2 – a – 1 = 0, then which one of the following could be the  [#permalink]

Show Tags

04 Jan 2019, 12:00
1
UB001 wrote:
If a^3 + a^2 – a – 1 = 0, then which one of the following could be the value of a?

(A) 0
(B) 1
(C) 2
(D) 3
(E) 4

$${a^3} + {a^2} = a + 1$$

$$?\,\,\,:\,\,\,{\rm{could}}\,\,{\rm{be}}\,\,a$$

Let´s do a trivial alternatives INSPECTION:

$$\left( A \right)\,\,0\mathop = \limits^? 1\,\,\,{\rm{no}}$$

$$\left( B \right)\,\,2\mathop = \limits^? 2\,\,\,{\rm{yes}}\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,? = 1\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\left( {\rm{B}} \right)$$

Regards,
Fabio.
_________________
Fabio Skilnik :: GMATH method creator (Math for the GMAT)
Our high-level "quant" preparation starts here: https://gmath.net
Re: If a^3 + a^2 – a – 1 = 0, then which one of the following could be the   [#permalink] 04 Jan 2019, 12:00
Display posts from previous: Sort by

If a^3 + a^2 – a – 1 = 0, then which one of the following could be the

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne