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# p and m are positive integers, and p is a prime number. If x

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p and m are positive integers, and p is a prime number. If x [#permalink]

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07 Sep 2013, 09:57
Hi,

Need your guidance for below qq.

p and m are positive integers, and p is a prime number. If x^2-mx+p=0 has a positive interger solution what is the value of (m-p)?

Last edited by Narenn on 08 Sep 2013, 18:31, edited 1 time in total.
Topic Moved. Always post the topic in relevant forum

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Re: p and m are positive integers, and p is a prime number. If x [#permalink]

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08 Sep 2013, 18:30
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alokgupta1009 wrote:
Hi,

Need your guidance for below qq.

p and m are positive integers, and p is a prime number. If x^2-mx+p=0 has a positive interger solution what is the value of (m-p)?

In any quadratic equation $$ax^2 + bx + c = 0$$, the relationship between b and c is that b is the sum of the factors of c*a.

In $$x^2 - mx + p = 0$$, we know -m is the sum of the factors of p, and we also know that p is the prime number that means it has only two factors, p and 1

So -m = -p -1 -------> m - p = 1

Hope that helps
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Re: p and m are positive integers, and p is a prime number. If x [#permalink]

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03 Jul 2014, 04:19
Narenn wrote:
alokgupta1009 wrote:
Hi,

Need your guidance for below qq.

p and m are positive integers, and p is a prime number. If x^2-mx+p=0 has a positive interger solution what is the value of (m-p)?

In any quadratic equation $$ax^2 + bx + c = 0$$, the relationship between b and c is that b is the sum of the factors of c*a.

In $$x^2 - mx + p = 0$$, we know -m is the sum of the factors of p, and we also know that p is the prime number that means it has only two factors, p and 1

So -m = -p -1 -------> m - p = 1

Hope that helps

I didn't understand the explanation. Could you elaborate and give a numerical example?

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MBA Section Director
Status: Back to work...
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City: Pune
GMAT 1: 680 Q49 V34
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Re: p and m are positive integers, and p is a prime number. If x [#permalink]

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04 Jul 2014, 05:49
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Expert's post
iftach1 wrote:
Narenn wrote:
alokgupta1009 wrote:
Hi,

Need your guidance for below qq.

p and m are positive integers, and p is a prime number. If x^2-mx+p=0 has a positive interger solution what is the value of (m-p)?

In any quadratic equation $$ax^2 + bx + c = 0$$, the relationship between b and c is that b is the sum of the factors of c*a.

In $$x^2 - mx + p = 0$$, we know -m is the sum of the factors of p, and we also know that p is the prime number that means it has only two factors, p and 1

So -m = -p -1 -------> m - p = 1

Hope that helps

I didn't understand the explanation. Could you elaborate and give a numerical example?

In quadratic equation $$x^2 + bx + c = 0$$, -b is the sum of the factors and c is the product. Suppose the factors of the equation are p and q then we can express $$x^2 + bx + c = 0$$ as $$x^2 + (p+q)x + pq = 0$$ where pq = c and p+q = -b
Consider the equation $$x^2 - 5x + 4 = 0$$ The factors of this equation are 4 & 1 so this equation can be expressed as $$x^2 - (4+1)x + (4*1) = 0$$

In the equation $$x^2 - mx + p = 0$$ we know that P is the prime number, so it can have only two factors: p and 1, so we can express the equation as $$x^2 - (p+1)x + (p*1) = 0$$. SO we have that -m = -p -1 and P = p ------> so m - p = p + 1 - p -----> 1

Hope that helps!!
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p and m are positive integers, and p is a prime number. If x [#permalink]

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05 Jul 2014, 01:10
Hi Narren,

Why you did not consider:-p+1=-m
Along with -p-1=-m I think above mentioned relation is also valid because m is sum or difference of factors.

Then -1 is also a possible value.
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p and m are positive integers, and p is a prime number. If x   [#permalink] 05 Jul 2014, 01:10
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