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.
What is the value of the expression 3 sqrt 80-2 sqrt 5
[#permalink]
24 May 2023, 05:48
24 May 2023, 05:48
Expert Reply
00:00
Question Stats:
72% (00:35) correct
27% (00:58) wrong based on 11 sessions
Hide Show timer Statistics
What is the value of the expression \(3 \sqrt{80} - 2 \sqrt{5}\) ?
A. \(4 \sqrt{5}\)
B. \(5 \sqrt{3}\)
C. \(10 \sqrt{5}\)
D. \(12 \sqrt{3}\)
E. \(20 \sqrt{5}\)
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our Project: Free GRE Prep Club Tests in Exchange for 20 Kudos
\(\Longrightarrow\) Cracking the GRE Premium
\(\Longrightarrow\) GRE Math Essentials - A most comprehensive handout!!
A. \(4 \sqrt{5}\)
B. \(5 \sqrt{3}\)
C. \(10 \sqrt{5}\)
D. \(12 \sqrt{3}\)
E. \(20 \sqrt{5}\)
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our Project: Free GRE Prep Club Tests in Exchange for 20 Kudos
\(\Longrightarrow\) Cracking the GRE Premium
\(\Longrightarrow\) GRE Math Essentials - A most comprehensive handout!!
Re: What is the value of the expression 3 sqrt 80-2 sqrt 5
[#permalink]
28 May 2023, 23:34
28 May 2023, 23:34
Expert Reply
OE
The problem is subtracting roots. Since roots cannot be subtracted unless the numbers under the radical sign are equal, look for a way to simplify the roots. Since 5 cannot be simplified any further, work with 80. The factors of 80 are 1 and 80, 2 and 40, 4 and 20, 5 and 16, and 8 and 10. Two of these pairs of factors contain a perfect square, but one contains a perfect square and a prime number. This is a good thing. This means that it could be reduced no further, so choose 5 and 16 and simplify to read
\(3 \sqrt{80}=3 \sqrt{5 *16} =3*4 \sqrt{5 }=12 \sqrt{5}\)
Now that the bases are equal, subtract the expression to find that \(12 \sqrt{5 }- 2 \sqrt{5}= 10 \sqrt{5}\)
The problem is subtracting roots. Since roots cannot be subtracted unless the numbers under the radical sign are equal, look for a way to simplify the roots. Since 5 cannot be simplified any further, work with 80. The factors of 80 are 1 and 80, 2 and 40, 4 and 20, 5 and 16, and 8 and 10. Two of these pairs of factors contain a perfect square, but one contains a perfect square and a prime number. This is a good thing. This means that it could be reduced no further, so choose 5 and 16 and simplify to read
\(3 \sqrt{80}=3 \sqrt{5 *16} =3*4 \sqrt{5 }=12 \sqrt{5}\)
Now that the bases are equal, subtract the expression to find that \(12 \sqrt{5 }- 2 \sqrt{5}= 10 \sqrt{5}\)
gmatclubot
Re: What is the value of the expression 3 sqrt 80-2 sqrt 5 [#permalink]
28 May 2023, 23:34
Moderators:
