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If x^2 - 3x + k = -30, what is the value of k?

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If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 10 Apr 2018, 06:34
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If x^2 - 3x + k = -30, what is the value of k?

(1) 2 is an element of the solution set of the given equation.
(2) 5 is an element of the solution set of the given equation.

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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 10 Apr 2018, 09:10
Bunuel wrote:
If x^2 - 3x + k = -30, what is the value of k?

(1) 2 is an element of the solution set of the given equation.
(2) 5 is an element of the solution set of the given equation.


x^2 - 3x + k = -30

we need value of x to find the value of k

from 1:

x=2
we can find the value of k by replacing the value of x in given eq.

sufficient.

from 2:

x=5

we can find the value of k by replacing the value of x in given eq.

sufficient

hence D
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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 10 Apr 2018, 09:47
x^2 - 3x + k = -30
x^2 - 3x + (k + 30) = 0

sum of roots = 3
product of roots = (k+30)

1) 2 + a = 3 => a = 1.
So, k+30 = 2 => k = 28

2) 5 + b = 3 => b = -2.
So, k + 30 = -10 => k = -40

EIther sufficient.

(D)
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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 10 Apr 2018, 23:21
(1). We know that 2 is the solution set, hence simply put that in the given equation & "k" can easily be deduced. Hence, SUFFICIENT.

(2). Similarly, this is also SUFFICIENT.

Hence, both are individually self sufficent to asnwer the question. Hence D
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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 11 Apr 2018, 06:04
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This one stumped me for awhile and I'm still not 100% sure. I thought for DS questions 1) and 2) are hints for the same answer. But if X=2 then k=-28. But if X=5 then k= -40. Am I calculating this incorrectly?

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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 11 Apr 2018, 06:07
Don't know lol....
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Re: If x^2 - 3x + k = -30, what is the value of k?  [#permalink]

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New post 11 Apr 2018, 06:08
dracobook wrote:
This one stumped me for awhile and I'm still not 100% sure. I thought for DS questions 1) and 2) are hints for the same answer. But if X=2 then k=-28. But if X=5 then k= -40. Am I calculating this incorrectly?

Sent from my Pixel 2 XL using GMAT Club Forum mobile app


You are right. The question is flawed. Archived.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
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Re: If x^2 - 3x + k = -30, what is the value of k? &nbs [#permalink] 11 Apr 2018, 06:08
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