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If m and n are the roots of the equation
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Updated on: 18 Aug 2018, 02:03
Updated on: 18 Aug 2018, 02:03
HI guys!
Question:
If m and n are the roots of the equation \(a^2 - 6a + 8 = 0\), then find the value of \((m+n)(m-n)\)
A. 12
B. 8
C. 16
D. 4
E.18
Now, the answer should be 12, because the fractioning of the equation gets me (a-4) (a-2). However, what if I switched places here and put (a-2) (a-4). Then, m = 2 and n=4, thus (2+4) (2-4) = -12. Where am I going wrong? Sorry for this stupid question. And btw, roots of the equation are always positive then, right?
Appreciate any help.
Question:
If m and n are the roots of the equation \(a^2 - 6a + 8 = 0\), then find the value of \((m+n)(m-n)\)
A. 12
B. 8
C. 16
D. 4
E.18
Now, the answer should be 12, because the fractioning of the equation gets me (a-4) (a-2). However, what if I switched places here and put (a-2) (a-4). Then, m = 2 and n=4, thus (2+4) (2-4) = -12. Where am I going wrong? Sorry for this stupid question. And btw, roots of the equation are always positive then, right?
Appreciate any help.
Re: If m and n are the roots of the equation
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18 Aug 2018, 02:13
18 Aug 2018, 02:13
Expert Reply
Hi,
before to post a question on the board, please, follow the rule fr posting here https://gre.myprepclub.com/forum/rules-for ... -1083.html and how to format a question here https://gre.myprepclub.com/forum/qq-how-to ... -2357.html
Moreover, post the question under the right section and not in general quant section.
Back to the question.
You are right m=2 n=4 in which case the answer is -12
But could be the other way around also: m=4 an n=2 which is 12
No a good question.
Regards
before to post a question on the board, please, follow the rule fr posting here https://gre.myprepclub.com/forum/rules-for ... -1083.html and how to format a question here https://gre.myprepclub.com/forum/qq-how-to ... -2357.html
Moreover, post the question under the right section and not in general quant section.
Back to the question.
You are right m=2 n=4 in which case the answer is -12
But could be the other way around also: m=4 an n=2 which is 12
No a good question.
Regards
Re: If m and n are the roots of the equation
[#permalink]
18 Aug 2018, 04:46
18 Aug 2018, 04:46
1
Appreciate the comments, Carcass. Sorry for being careless, and thank you for the clarification on the question.
However, I think you made a mistake there. If m=4 and n=2, then (m+n)(m−n) = (4+2) (4-2) = 12. I doesn't make a whole lot of difference though, because I guess we just established that this is not a well-thought-out question.
Thanks!
However, I think you made a mistake there. If m=4 and n=2, then (m+n)(m−n) = (4+2) (4-2) = 12. I doesn't make a whole lot of difference though, because I guess we just established that this is not a well-thought-out question.
Thanks!
