GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 06 Dec 2019, 10:49

### GMAT 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

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 59587
Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o  [#permalink]

### Show Tags

19 Mar 2019, 02:03
00:00

Difficulty:

15% (low)

Question Stats:

86% (01:24) correct 14% (01:48) wrong based on 35 sessions

### HideShow timer Statistics

Let d and e denote the solutions of $$2x^{2}+3x-5=0$$. What is the value of (d-1)(e-1)?

(A) -5/2
(B) 0
(C) 3
(D) 5
(E) 6

_________________
Intern
Joined: 14 Jan 2016
Posts: 9
Location: India
Concentration: Finance, Marketing
Re: Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o  [#permalink]

### Show Tags

19 Mar 2019, 02:15
Bunuel wrote:
Let d and e denote the solutions of $$2x^{2}+3x-5=0$$. What is the value of (d-1)(e-1)?

(A) -5/2
(B) 0
(C) 3
(D) 5
(E) 6

We can solve $$2x^{2}+3x-5=0$$ to get solutions as -5/2 & 1.
Value = (d-1)(e-1)

Since (d-1) or (e-1) will be equal to 0 as one of the root is 1.
So value of (d-1)(e-1) = (-5/2 - 1)(1-1) = 0 (Option B)
GMAT Club Legend
Joined: 18 Aug 2017
Posts: 5428
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o  [#permalink]

### Show Tags

19 Mar 2019, 06:03
Bunuel wrote:
Let d and e denote the solutions of $$2x^{2}+3x-5=0$$. What is the value of (d-1)(e-1)?

(A) -5/2
(B) 0
(C) 3
(D) 5
(E) 6

solve
$$2x^{2}+3x-5=0$$
we get
-5/2 * 1
so
(+1-1)*(-5/2-1)
0
IMO b
Senior Manager
Joined: 12 Sep 2017
Posts: 308
Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o  [#permalink]

### Show Tags

19 Mar 2019, 18:37
Using Viete's theorem:

$$2x^2 + 3x-5=0$$

$$Sum: \frac{-b}{a}$$

$$\frac{-3}{2}$$

$$Prod: \frac{c}{a}$$

$$\frac{-5}{2}$$

Given: $$(d-1)(e-1)$$ = $$de$$ $$-d -e$$ $$+1$$ =

$$de$$ $$- (d+e$$) $$+1$$

$$\frac{-5}{2} - (\frac{-3}{2}) + 1$$

$$\frac{-5}{2} + \frac{3}{2}$$ $$+ 1$$

$$\frac{-2}{2} = -1$$ $$+ 1$$ $$= 0$$

B
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8619
Location: United States (CA)
Re: Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o  [#permalink]

### Show Tags

21 Mar 2019, 18:02
Bunuel wrote:
Let d and e denote the solutions of $$2x^{2}+3x-5=0$$. What is the value of (d-1)(e-1)?

(A) -5/2
(B) 0
(C) 3
(D) 5
(E) 6

Solving for x, we have:

(2x + 5)(x - 1) = 0

2x + 5 = 0

2x = -5

x = -5/2

or

x = 1

Thus,

(d - 1)(e - 1) = (-2.5 - 1)(1 - 1) = 0

Alternate solution:

We can use the following fact:

If r and s are solutions (or roots) of the quadratic equation ax^2 + bx + c = 0 (where a ≠ 0), then r + s = -b/a and rs = c/a.

Here, since d and e are solutions of 2x^2 + 3x - 5 = 0, then d + e = -3/2 and de = -5/2. Therefore, we have:

(d - 1)(e - 1) = de - d - e + 1 = de - (d + e) + 1 = -5/2 - (-3/2) + 1 = 0

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Re: Let d and e denote the solutions of 2x^2 + 3x-5=0. What is the value o   [#permalink] 21 Mar 2019, 18:02
Display posts from previous: Sort by