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If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ?

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Bunuel
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If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   02 Dec 2014, 09:05
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Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT
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B
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manpreetsingh86
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   02 Dec 2014, 10:44
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Bunuel wrote:

Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT


\(g(3) =\sqrt{3^2+7}\)
\(g(3)= \sqrt{16}\)
\(g(3)=4\) (discard -4 because square root of negative numbers are not allowed in gmat.)
thus, \(f(g(3)= \sqrt{4}\)
\(f(g(3)=2\)
hence option B
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   02 Dec 2014, 11:16
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First, calculate g(3) = square root of 9 + 7, which is 4

Now, calculate f(4) = square root of 2

Discard all negative roots because GMAT accepts only positive roots.

Answer is B
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   02 Dec 2014, 18:51
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Answer = B) 2

\(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\)

\(f(g(x)) = (\sqrt{x^2 + 7})^{(\frac{1}{2})} = (x^2 + 7)^{(\frac{1}{4})}\)

\(f(g(3)) = (3^2 + 7)^{(\frac{1}{4})} = (2^4)^{(\frac{1}{4})} = 2\)
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   03 Dec 2014, 07:48
Expert Reply
Bunuel wrote:

Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT


The correct answer is B.

Check other function questions in our Special Questions Directory:

Operations/functions defining algebraic/arithmetic expressions
Symbols Representing Arithmetic Operation
Rounding Functions
Various Functions
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   01 Aug 2017, 08:37
Very Easy just 20 second question
option B
g(3)=√3^2+7
g(3)=√9+7
g(3)=√16=4
now put 4 in f(x)
f(4)=√4=2
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   05 Feb 2021, 05:10
manpreetsingh86 wrote:
Bunuel wrote:

Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT


\(g(3) =\sqrt{3^2+7}\)
\(g(3)= \sqrt{16}\)
\(g(3)=4\) (discard -4 because square root of negative numbers are not allowed in gmat.)
thus, \(f(g(3)= \sqrt{4}\)
\(f(g(3)=2\)
hence option B
I need more help in understanding how this is done. where does the number 3 taken for the value of x, is it an assumption of a value ? Can someone help with the explanation of basics please
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Animeshmishrra
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   05 Feb 2021, 05:10
manpreetsingh86 wrote:
Bunuel wrote:

Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT


\(g(3) =\sqrt{3^2+7}\)
\(g(3)= \sqrt{16}\)
\(g(3)=4\) (discard -4 because square root of negative numbers are not allowed in gmat.)
thus, \(f(g(3)= \sqrt{4}\)
\(f(g(3)=2\)
hence option B
I need more help in understanding how this is done. where does the number 3 taken for the value of x, is it an assumption of a value ? Can someone help with the explanation of basics please
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink] New post   02 Jan 2024, 08:33
Bunuel wrote:

Tough and Tricky questions: Functions.



If \(f(x) = \sqrt{x}\) and \(g(x) = \sqrt{x^2 + 7}\), what is the value of f(g(3)) ?

A) 1
B) 2
C) 3
D) 4
E) 5

Kudos for a correct solution.

Source: Chili Hot GMAT

\(g(3) = \sqrt{3^2 + 7}=4\)

Now, \(f(g(3)) = \sqrt{4}=2\), Answer must be (B) 2
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Re: If f(x) = x and g(x) = x^2 + 7 , what is the value of f(g(3)) ? [#permalink]
02 Jan 2024, 08:33
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