Last visit was: 22 Dec 2024, 21:20 It is currently 22 Dec 2024, 21:20

Close

GRE Prep 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 GRE 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.

Close

Request Expert Reply

Confirm Cancel
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36823 [1]
Given Kudos: 26100
Send PM
Retired Moderator
Joined: 29 Mar 2020
Posts: 140
Own Kudos [?]: 332 [0]
Given Kudos: 24
Send PM
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3267 [1]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Manager
Manager
Joined: 25 Aug 2020
Posts: 80
Own Kudos [?]: 67 [0]
Given Kudos: 65
Send PM
Re: The function f(x)=2x^2 [#permalink]
Hi,

Can we assume that (f*g) is always composite function, (f*g)(x) = f(g(x)) in GRE ?


Best,
Gocha
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36823 [1]
Given Kudos: 26100
Send PM
Re: The function f(x)=2x^2 [#permalink]
1
Expert Reply
Gocha wrote:
Hi,

Can we assume that (f*g) is always composite function, (f*g)(x) = f(g(x)) in GRE ?


Best,
Gocha


No Sir as far as I know

it depends on the stem
Manager
Manager
Joined: 25 Aug 2020
Posts: 80
Own Kudos [?]: 67 [0]
Given Kudos: 65
Send PM
Re: The function f(x)=2x^2 [#permalink]
Carcass wrote:
Gocha wrote:
Hi,

Can we assume that (f*g) is always composite function, (f*g)(x) = f(g(x)) in GRE ?


Best,
Gocha


No Sir as far as I know

it depends on the stem


Hi Carcass,

Understood, thank you for clarifying. Is there any reason that we can determine that (f*g)(x) is composite in this stem ?

Best,
Gocha
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36823 [1]
Given Kudos: 26100
Send PM
The function f(x)=2x^2 [#permalink]
1
Expert Reply
In this case, the multiplication implies that

\((f \times g )(-2)= f(g(-2))= f \times g(-2)\)
Manager
Manager
Joined: 25 Aug 2020
Posts: 80
Own Kudos [?]: 67 [0]
Given Kudos: 65
Send PM
Re: The function f(x)=2x^2 [#permalink]
Carcass wrote:
In this case, the multiplication implies that

\((f \times g )(-2)= f(g(-2))= f \times g(-2)\)


Ok, thank you Carcass, I will learn more.
Verbal Expert
Joined: 18 Apr 2015
Posts: 30475
Own Kudos [?]: 36823 [0]
Given Kudos: 26100
Send PM
Re: The function f(x)=2x^2 [#permalink]
Expert Reply
No worries so much about function on the GRE. They are not tested so much

This question is more like a strange symbol question, solving by substitution. Is more algebra as you can see above rather than function itself
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3267 [0]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: The function f(x)=2x^2 [#permalink]
Gocha wrote:
Hi,

Can we assume that (f*g) is always composite function, (f*g)(x) = f(g(x)) in GRE ?


Best,
Gocha


Yes that is what composite or nested functions are
Moderator
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Own Kudos [?]: 974 [1]
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
Send PM
Re: The function f(x)=2x^2 [#permalink]
1
\(f(x)=2x^2-5x\) and \(g(x)=x^2+x-3\)

And we need to find the value of \((f*g)(-2)-[f(3)+g(2)]\)

\((f*g)(-2)\) = \(f(g(-2))\)
Let's find g(-2) first we get
\(g(-2)=(-2)^2 + -2-3\) [ Substitute x=-2 in g(x) ]
\(g(-2) = 4 - 5 = -1\)

f(g(-2)) = f(-1)
\(f(-1)=2(-1)^2 - 5*(-1)\) [ Substitute x=-1 in f(x) ]
= 2 + 5 = 7

f(3)
\(f(3)=2*(3)^2-5*(3)\) = 18 - 15 = 3

g(2)
\(g(2)=2^2+2-3\) = 4-1 = 3

\((f*g)(-2)-[f(3)+g(2)]\) = 7 - (3+3) = 7 - 6 =1

So, answer will be D
Hope it helps!

To learn more about Functions watch the following video

Prep Club for GRE Bot
Re: The function f(x)=2x^2 [#permalink]
Moderators:
GRE Instructor
88 posts
GRE Forum Moderator
37 posts
Moderator
1115 posts
GRE Instructor
234 posts

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