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# x# = x2 + 3x x§ = x2 + 2x

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x# = x2 + 3x x§ = x2 + 2x [#permalink]  24 Mar 2018, 02:27
Expert's post
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Question Stats:

49% (01:12) correct 49% (01:29) wrong based on 14 sessions
x# $$= x^2 + 3x$$
x$$$= x^2 + 2x$$  Quantity A Quantity B (x$)# (x#)$A. Quantity A is greater. B. Quantity B is greater. C. The two quantities are equal. D. The relationship cannot be determined from the information given. Drill 1 Question: 8 Page: 547 [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 Intern Joined: 20 Dec 2017 Posts: 30 Followers: 0 Kudos [?]: 16 [0], given: 9 Re: x# = x2 + 3x x§ = x2 + 2x [#permalink] 25 Mar 2018, 10:54 sandy wrote: x# $$= x^2 + 3x$$ x$ $$= x^2 + 2x$$

 Quantity A Quantity B (x$)# (x#)$

A. Quantity A is greater.
B. Quantity B is greater.
C. The two quantities are equal.
D. The relationship cannot be determined from the information given.

Drill 1
Question: 8
Page: 547

Why not C
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Re: x# = x2 + 3x x§ = x2 + 2x [#permalink]  25 Mar 2018, 19:06
1
KUDOS
yell2012prime wrote:
sandy wrote:
x# $$= x^2 + 3x$$
x$$$= x^2 + 2x$$  Quantity A Quantity B (x$)# (x#)$A. Quantity A is greater. B. Quantity B is greater. C. The two quantities are equal. D. The relationship cannot be determined from the information given. Drill 1 Question: 8 Page: 547 Why not C x can be 0 GRE Prep Club Legend Joined: 07 Jun 2014 Posts: 4856 GRE 1: Q167 V156 WE: Business Development (Energy and Utilities) Followers: 102 Kudos [?]: 1741 [1] , given: 397 Re: x# = x2 + 3x x§ = x2 + 2x [#permalink] 28 Mar 2018, 13:37 1 This post received KUDOS Expert's post Explanation Whenever you have a function within another function, you have to first calculate the value of the function on the inside, and then plug that value into the function on the outside. Plug in to test the values. If you plug in 2 for x, then, in Quantity A, 2$ = $$2^2 + 2(2) = 8$$and 8# =$$8^2 + 3(8) = 88$$; in Quantity B, 2# = $$2^2 + 3(2) = 10$$ and 10\$ = $$10^2 + 2(10) = 120$$; eliminate choices (A) and (C).

However, if you plug in 0 for x, then both quantities are 0; eliminate choice (B), and you’re left with choice (D), the correct answer.
_________________

Sandy
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Re: x# = x2 + 3x x§ = x2 + 2x [#permalink]  29 Mar 2018, 05:20
Well, this is a tricky question.. because (XS)# is not a function like f(g(x)) that you have to solve the inner function and use the value in the encompassing function as @ Sandy noted above. The figure (XS)# and (x#)S are both multiplication of function, not a function within a function. So the answer could be "C"... because both resolve to X^3+5X^2+6X.
Re: x# = x2 + 3x x§ = x2 + 2x   [#permalink] 29 Mar 2018, 05:20
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