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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
If x ≥ 0, then must be equal to 0.07x8 0.07x4 0.7x14 0.7x8 0
[#permalink]
27 Oct 2018, 16:47
27 Oct 2018, 16:47
Expert Reply
2
Bookmarks
00:00
Question Stats:
72% (00:34) correct
27% (00:33) wrong based on 77 sessions
Hide Show timer Statistics
If x ≥ 0, \(\sqrt{0.49x^{16}}\)then must be equal to
A. \(0.07x^8\)
B. \(0.07x^4\)
C. \(0.7x^{14}\)
D. \(0.7x^8\)
E. \(0.7x$4\)
A. \(0.07x^8\)
B. \(0.07x^4\)
C. \(0.7x^{14}\)
D. \(0.7x^8\)
E. \(0.7x$4\)
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: If x ≥ 0, then must be equal to 0.07x8 0.07x4 0.7x14 0.7x8 0
[#permalink]
28 Oct 2018, 07:32
28 Oct 2018, 07:32
1
1
Bookmarks
sandy wrote:
If x ≥ 0, \(\sqrt{0.49x^{16}}\)then must be equal to
A. \(0.07x^8\)
B. \(0.07x^4\)
C. \(0.7x^{14}\)
D. \(0.7x^8\)
E. \(0.7x$4\)
A. \(0.07x^8\)
B. \(0.07x^4\)
C. \(0.7x^{14}\)
D. \(0.7x^8\)
E. \(0.7x$4\)
Useful property: \(\sqrt{xy} = (\sqrt{x})(\sqrt{y})\)
So, \(\sqrt{0.49x^{16}} = (\sqrt{0.49})(\sqrt{x^{16}})\)
\(= (0.7)(x^8)\)
Answer: D
ASIDE: A common mistake is to conclude that \(\sqrt{x^{16}} = x^4\)
However, notice that \((x^4)(x^4) = x^8\), not \(x^{16}\)
Conversely, \((x^8)(x^8) = x^{16}\)
Re: If x ≥ 0, then must be equal to 0.07x8 0.07x4 0.7x14 0.7x8 0
[#permalink]
14 Jun 2020, 10:23
14 Jun 2020, 10:23
Since √x = x^1/2, can I say that √x^16 = x^(16/2) = x^8 ?
