I was given the following question to answer. But I am currently stuck on the last part.
The question is as follows: a) Find gcd(342,2240) call it g
b) find integers x,y such that 342x+2240y=g
c) Find another pair of integers, call the a and b, such that 342a+2240b=g
For part A:
2 ways I solved. First I used prime factorization of each number
342=2∗32∗19 and 2240=26∗5∗7 and found the gcd, g was 2.
Another way was the Euclidean algorithm:
2240=342∗6+188
342=188∗1+154
188=154∗1+34
154=34∗4+18
34=18∗1+16
18=16∗1+2
16=2∗8+0 leaving me with the gcd, g was 2
Part B:
Working from the algorithm backwards I can find it or do division and work backwards.
So:
2=18−1∗16
=18−1(34−1∗18)
=2∗18−1∗34
=2(154∗−4∗34)−1∗34
=2∗154−9∗34
=2∗154−9(188−1∗154)
=11∗154−9∗188
=11(342−1∗188)−9∗188
$=11*342-20*188
=11∗342−20(2240−6∗342)
=131∗342−20∗2240
Which leaves me with 342(131)+2240(−20)=g were g=2
Did I leave this statement correctly?
And how exactly do I find 2 additional number a,b if you can assist with this problem, direct me to one or do a smaller but similar question with it I would appreciate it.
Answer
Just solve the homogeneous equation 342x+2240y=0. For example x=2240, y=−342 would be a solution. Then x+x0 and y+y0 is a new solution of your original equation, where x0,y0 is the solution of non-homogeneous equation 342x+2240y=g
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