BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

x denotes the decimal fraction part of

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

x denotes the decimal fraction part of

by Max@Math Revolution » Mon Mar 09, 2020 8:30 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

[GMAT math practice question]

x denotes the decimal fraction part of \(\sqrt{57}\) . What is x(x + 14)?

A. 6
B. 7
C. 8
D. 9
E. 10
Top
Source: — Problem Solving |
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

Re: x denotes the decimal fraction part of

by Max@Math Revolution » Thu Mar 12, 2020 12:13 am
=>


7 = √49 < √57 < √64 = 8
We have x = √57 – 7 since x denotes the decimal fraction part of √57.

Then
x(x + 14) = (√57 – 7)(√57 + 14 - 7)
x(x + 14) = (√57 – 7)(√57 + 7) (adding like terms)
x(x + 14) = 57 + 7√57 - 7√57 – 49 (foiling the right side)
x(x + 14) = 57 – 49 (cancelling terms)
x(x + 14) = 8 (adding like terms)

Therefore, C is the answer.
Answer: C
Top
Post new topic Post Reply
• Page 1 of 1