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M7MBA: Moderator; Posts: 2058; Joined: Sun Oct 29, 2017 4:24 am; Thanked: 1 times; Followed by:5 members

If y= 4 + (x - 3)^2, then y is lowest when

by M7MBA » Tue Jun 25, 2019 6:06 am

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If \(y= 4 + (x - 3)^2,\) then \(y\) is lowest when \(x =\)

A. 14
B. 13
C. 0
D. 3
E. 4

The OA is the option _D_

Source: Official Guide

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Source: Beat The GMAT — Problem Solving | Tue Jun 25, 2019 6:06 am

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Tue Jun 25, 2019 6:13 am

M7MBA wrote:If \(y= 4 + (x - 3)^2,\) then \(y\) is lowest when \(x =\)

A. 14
B. 13
C. 0
D. 3
E. 4

KEY CONCEPT: In order to minimize the value of y, we must minimize the value of (x -3)Â²

We know that (some number)Â² â‰¥ 0
So, the SMALLEST possible value of (some number)Â² is 0

Likewise, the SMALLEST possible value of (x -3)Â² is 0
(x -3)Â² = 0 when x = 3

Answer: D

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members