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

 It is currently 11 Dec 2019, 23:18

### 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

# If the sum of the reciprocals of the roots of the equation ax^2+bx+c=0

Author Message
TAGS:

### Hide Tags

Manager
Joined: 18 Jul 2019
Posts: 54
If the sum of the reciprocals of the roots of the equation ax^2+bx+c=0  [#permalink]

### Show Tags

24 Nov 2019, 23:21
4
00:00

Difficulty:

65% (hard)

Question Stats:

35% (01:55) correct 65% (02:07) wrong based on 17 sessions

### HideShow timer Statistics

If the sum of the reciprocals of the roots of the equation $$ax^2 + bx + c = 0$$ is $$11/28$$ and the product of the roots of the equation $$cx^2 + bx + a = 0$$ is $$1/28$$, find the sum of the roots of the equation $$bx^2 +ax+ c = 0$$

(A) 28/11
(B) -28/11
(C) 1/11
(D) -1/11
(E) -1/28
Math Expert
Joined: 02 Aug 2009
Posts: 8305
Re: If the sum of the reciprocals of the roots of the equation ax^2+bx+c=0  [#permalink]

### Show Tags

28 Nov 2019, 05:56
CaptainLevi wrote:
If the sum of the reciprocals of the roots of the equation $$ax^2 + bx + c = 0$$ is $$11/28$$ and the product of the roots of the equation $$cx^2 + bx + a = 0$$ is $$1/28$$, find the sum of the roots of the equation $$bx^2 +ax+ c = 0$$

(A) 28/11
(B) -28/11
(C) 1/11
(D) -1/11
(E) -1/28

The sum of the reciprocals of the roots of the equation $$ax^2 + bx + c = 0$$ is $$11/28$$
If x and y are roots, the reciprocal and their sum = $$\frac{1}{x}+\frac{1}{y}=\frac{x+y}{xy}=\frac{Sum}{Product}=\frac{\frac{-b}{a}}{\frac{c}{a}}=\frac{-b}{c}=\frac{11}{28}$$..

the product of the roots of the equation $$cx^2 + bx + a = 0$$ is $$1/28$$ ------ $$\frac{a}{c}=\frac{1}{28}$$,

find the sum of the roots of the equation $$bx^2 +ax+ c = 0$$ ----$$\frac{-a}{b}=\frac{a}{c}*\frac{c}{-b}=\frac{1}{28}*\frac{28}{11}=\frac{1}{11}$$

C
_________________
Re: If the sum of the reciprocals of the roots of the equation ax^2+bx+c=0   [#permalink] 28 Nov 2019, 05:56
Display posts from previous: Sort by