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Find the smallest positive integer b for which x2+bx+2008 factors into a product of two binomials, each having integer coefficients.

 Feb 28, 2021
 #1
avatar+506 
+1

The factors of 2008 in pairs are (1,2008),(2,1004),(4,502),(8,251). The sum of the factors closest to each other will yield the smallest possible value for b, so the answer is 8+251=259

The factored quadratic would look like this: (x+8)(x+251)

 Feb 28, 2021
 #2
avatar+118703 
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jxt516:

 

Why don't you respond to my question? 

 

It is rude to not respond.

 

https://web2.0calc.com/questions/help-please_88636

 Mar 1, 2021
edited by Melody  Mar 1, 2021
 #3
avatar+118703 
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jxc, please explain to us how Textot got his answer.   Explain the reasoning behind it.

 

If you do not know then ask Textot questions about it.

Encourage or even push him/her to guide you through it.

 Mar 1, 2021
edited by Melody  Mar 1, 2021
 #4
avatar+201 
+1

I think you factor 2008, and using FOIL you find that (8,251) is the smallest

 

I might be wrong though

jxc516  Mar 1, 2021
 #5
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Since you do not understand you will need to ask Textot to explain.

Melody  Mar 1, 2021
 #6
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Oh wait I think I understand

 

When you use foil to expand, you multiply the variables together, then the sum of the products of the inside and outside terms, and the constants. Example: (x+2)(x-3)=x^2-x-6. 

 

Because of this, we need to factorize 2008, so for the middle term we get  x+2008x=2009x, 2x+1004x=1006x, 4x+502x=506x, 8x+251x=259x, and we take the smallest coefficient and that's our answer

jxc516  Mar 1, 2021
 #7
avatar+118703 
+2

I think you have it!  Good work!

 

For any quadratic  ax2+bx+c

 

if the roots are α and β

 

then

 

α+β=ba

 

and

 

αβ=ca

 

 

So in this case the roots multiply to 2008/1 =2008

Melody  Mar 1, 2021

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