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    Im doing the following excersice on congruencies but I dont have an answer book (and nobody to help me with it) so I just want to check my answers (and get help if I'm wrong).

    Divide out the common factors in the following congruencies
    i. 6a \equiv 6b (mod 20)
    ii. 23 \equiv 138 (mod 5)
    iii. 12 \equiv 30 (mod 9)

    My answers are:
    i.  a \equiv b (mod 10)
    ii.  1 \equiv 6 (mod 5)
    iii. 2 \equiv 3 (mod 3)

    This topic is so confusing but I really want to get my head around it.
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    I'm really no good at these at all, but your answer to iii looks wrong to me.
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    (Original post by ttoby)
    I'm really no good at these at all, but your answer to iii looks wrong to me.
    ahhh I see now oops XD idnt really check them. This might be better I guess;

    2 \equiv 5 (mod 3)
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    (Original post by Tobedotty)
    Im doing the following excersice on congruencies but I dont have an answer book (and nobody to help me with it) so I just want to check my answers (and get help if I'm wrong).

    Divide out the common factors in the following congruencies
    i. 6a \equiv 6b (mod 20)
    ii. 23 \equiv 138 (mod 5)
    iii. 12 \equiv 30 (mod 9)

    My answers are:
    i.  a \equiv b (mod 10)
    ii.  1 \equiv 6 (mod 5)
    iii. 2 \equiv 3 (mod 3)

    This topic is so confusing but I really want to get my head around it.
    i. Agreed.

    Not sure what they are getting at with the next two. Question seems weird to me, but:

    ii) Agreed.

    iii) Nope you can't take that factor of 3 out as 3 divides 9, check your working on that one.

    Edit: Your answer in post #3 is incorrect as well I think

    Edit2: Although it's actually a true statement, I don't think you can get there from taking out factors in the question.
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    (Original post by ghostwalker)

    Not sure what they are getting at with the next two. Question seems weird to me
    same, you could just mod out to begin with but I think its just so that you unerstand the principle behind divison in congruencies (especially seeing as the next section is about linear congruencies)

    I still need to check my workings (getting confused again :rolleyes: )
 
 
 

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