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

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATBootcamp Starts Sep 21
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE BOOTCAMP

Live Online Bootcamp Class with Top GMAT Expert Chris Peckover

Sep 21 to Oct 9, 2026

Schedule
Mon to Fri · 7:00 to 10:00 PM ET
Included
Live classes + 6 months of TTP OnDemand
  • Boost your GMAT score in less than one month in a live online class
  • 6 months access to TTP OnDemand video courses included
View bootcamp & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

What is the sum of roots of the equation x^2 – 40x + 399 =

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 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times
by Max@Math Revolution » Thu Sep 06, 2018 12:30 am

Timer

00:00

Answers

A

B

C

D

E

Stats

Difficulty—

[Math Revolution GMAT math practice question]

What is the sum of roots of the equation x^2 - 40x + 399 = 0?

A. 19
B. 20
C. 21
D. 40
E. 399
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 416
Joined: Thu Oct 15, 2009 11:52 am
Thanked: 27 times

What is the sum of roots of the equation x^2 - 40x + 399 =

by regor60 » Thu Sep 06, 2018 4:53 am
Max@Math Revolution wrote:[Math Revolution GMAT math practice question]

What is the sum of roots of the equation x^2 - 40x + 399 = 0?

A. 19
B. 20
C. 21
D. 40
E. 399
x^2-40x+ 399 = (x^2-40x +400) -1 = 0

x^2-40x+400 = 1

(x-20)^2 = 1

x-20 = 1 or -1

x=21 and 19

Sum = D, 40
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Thu Sep 06, 2018 5:49 am
Max@Math Revolution wrote:[Math Revolution GMAT math practice question]

What is the sum of roots of the equation x^2 - 40x + 399 = 0?

A. 19
B. 20
C. 21
D. 40
E. 399
For any quadratic in the form x² + bx + c = 0:
Sum of the roots = -b.
Product of the roots = c.

In the given quadratic, b = -40.
Thus, the sum of the roots = -b = -(-40) = 40.

The correct answer is D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 416
Joined: Thu Oct 15, 2009 11:52 am
Thanked: 27 times

by regor60 » Thu Sep 06, 2018 7:39 am
GMATGuruNY wrote:
Max@Math Revolution wrote:[Math Revolution GMAT math practice question]

What is the sum of roots of the equation x^2 - 40x + 399 = 0?

A. 19
B. 20
C. 21
D. 40
E. 399
For any quadratic in the form x² + bx + c = 0:
Sum of the roots = -b.
Product of the roots = c.

In the given quadratic, b = -40.
Thus, the sum of the roots = -b = -(-40) = 40.

The correct answer is D.
doh!<i class="em em---1"></i>
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times

by Max@Math Revolution » Sun Sep 09, 2018 5:19 pm
=>

Let p and q be the roots of the equation x^2 - 40x + 399 = 0.
Then x^2 - 40x + 399 = (x-p)(x-q) = x^2 - (p+q)x + pq.
Equating coefficients gives p + q = 40 from the coefficient of x.

Therefore, the answer is D.
Answer: D
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8198
Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members
Location: Los Angeles, CA
Thanked: 43 times

by Scott@TargetTestPrep » Mon Sep 17, 2018 5:31 pm
Max@Math Revolution wrote:[Math Revolution GMAT math practice question]

What is the sum of roots of the equation x^2 - 40x + 399 = 0?

A. 19
B. 20
C. 21
D. 40
E. 399
In a quadratic equation of the form ax^2 + bx + c = 0, the sum of the roots is -b/a. Therefore, here the sum of the roots is -(-40)/1 = 40.

Answer: D

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1