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Roots in common with x2-6x+5=0

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Roots in common with x2-6x+5=0

by sweet83 » Mon Mar 09, 2009 7:21 pm

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Which of the following equation has roots common with x2-6x+5=0?

a. x2+1 = 0
b. x2-x-2=0
c. x2-10x-5=0
d. 2x2-2=0
e. x2-2x-3=0

Answer is D. (sorry dont know how to hide the answer!)

This is simple problem, but i not able to understand the official answer. (x-5) (x-1) = 0, so factors are 5 and 1.

The official answers picked D has substituting 1 in the equation results in 0.

Why did we not substitute 5? If we do so then D doesn't make sense.

This problem is from Veritas prep material

Thanks everyone!
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by devesh99 » Mon Mar 09, 2009 7:35 pm
Hi

Probably the reason for choosing D was because it has at least 1 matching root. In the remaining options, there are no matches at all.
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by sweet83 » Mon Mar 09, 2009 8:26 pm
hmmm good point

thanks!!
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Re: Roots in common with x2-6x+5=0

by sureshbala » Mon Mar 09, 2009 11:25 pm
sweet83 wrote:Which of the following equation has roots common with x2-6x+5=0?

a. x2+1 = 0
b. x2-x-2=0
c. x2-10x-5=0
d. 2x2-2=0
e. x2-2x-3=0

Answer is D. (sorry dont know how to hide the answer!)

This is simple problem, but i not able to understand the official answer. (x-5) (x-1) = 0, so factors are 5 and 1.

The official answers picked D has substituting 1 in the equation results in 0.

Why did we not substitute 5? If we do so then D doesn't make sense.

This problem is from Veritas prep material

Thanks everyone!
I think instead of asking "common roots" it should be "common root"
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by adilzuberi » Wed Oct 21, 2009 3:11 pm
The Answer is D because only D has root in common with the given equation. 2(x^2 - 1) gives x = 1.. where initial equation has 5 and 1.
Note: The question did not ask for all the common roots, but only one common root.
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by Jeff@TargetTestPrep » Thu Jun 21, 2018 4:08 pm
sweet83 wrote:Which of the following equation has roots common with x2-6x+5=0?

a. x2+1 = 0
b. x2-x-2=0
c. x2-10x-5=0
d. 2x2-2=0
e. x2-2x-3=0
Simplifying the given equation, we have:

x^2 - 6x + 5 = 0

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

x = 5 or x = 1

By scanning through the answer choices, we see x = 1 is a solution to 2x^2 - 2 = 0. Thus, choice D is the answer.

Answer: D.

Jeffrey Miller
Head of GMAT Instruction
[email protected]

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