Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a question I can not figure out (It's #2 in section 4.4 of the book Discrete and Combinatorial Mathematics, by Ralph P. Grimaldi).

$\mathbb{Z}^+$ = The set of all positive integers

$\mathbb{Z}$ = The set of all integers

For $a, b \in \mathbb{Z}^+$ and $s,t \in \mathbb{Z}$, what can we say about $\gcd(a,b)$ if:

$as + bt = 2$?

share|cite|improve this question
    
look at this en.wikipedia.org/wiki/B%C3%A9zout%27s_identity – jim Feb 28 '13 at 3:17

HINT: If $d\mid a$ and $d\mid b$, what else in the equation $as+bt=2$ must be divisible by $d$? You might also want to look up Bézout’s theorem.

share|cite|improve this answer

Hint $\rm\:d\mid a,b\:\Rightarrow\:d\mid as+bt = 2$

share|cite|improve this answer
1  
oh this is better – Carry on Smiling Feb 28 '13 at 3:20

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.