Online Course Discussion Forum

MCIII Number Theory 5.19

 
 
Picture of Tina Jin
MCIII Number Theory 5.19
by Tina Jin - Tuesday, 2 January 2024, 11:57 AM
 

Hello!

I need some help on this problem, I tried this:

ab-cd | ab

ab-cd | cd

And other equations like that.

What should I do now? 

Thanks,

Tina Jin

 
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Re: MCIII Number Theory 5.19
by Dr. Kevin Wang - Saturday, 6 January 2024, 1:27 AM
 

Let $k=ab-cd$.  Since $k$ is a factor of $a$, $b$, $c$, and $d$, we can let $a=xk$, $b=yk$, $c=zk$, and $d=wk$.  

Picture of Tina Jin
Re: MCIII Number Theory 5.19
by Tina Jin - Sunday, 14 January 2024, 12:38 PM
 

Oh! I got 1=k(xy-zw) which means k=1! Thank you!

Picture of Dr. Kevin Wang
Re: MCIII Number Theory 5.19
by Dr. Kevin Wang - Monday, 15 January 2024, 11:11 PM
 

Very good!