Diophantine Equation

Trumbone

New member
Joined
Oct 5, 2009
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I am looking for some help in solving the equation
15 625x + 8404 = 1024y

Thank you
 
I will step through this one. Keep it as a guide so you can attempt others. Okey-doke?.

15625x1024y=8404\displaystyle 15625x-1024y=-8404

Find GCD(15625, -1024):

-1024=(-1)15625+14601

15625=14601(1)+1024

14601=1024(14)+265

1024=265(3)+229

265=229(1)+36

229=36(6)+13

36=13(2)+10

13=10(1)+3

3=3(1)+0

GCD=1

Now, back substitute to find the linear combination so we can express the GCD in terms of -1024 and 15625:

1=(1*10)+(-3*3)

=(-3*13)+(4*10)

=(4*36)+(-11*13)

=(-11*229)+(70*36)

=(70*265)+(-81*229)

=(-81*1024)+(313*265)

=(313*14601)+(-4463*1024)

=(-4463*15625)+(4776*14601)

=1024(4776)+15625(313)\displaystyle -1024(4776)+15625(313)

Therefore, a particular solution is

x=-2630452 and y=-40137504

The general solution works out to be

x=-2630452+1024t and y=-40137504+15625t

It is tedious, but is pretty cool once you get the hang of it.
 
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