Finding gcd of two unknowns included in this linear diophantine equation

diophantine equationsgcd-and-lcmnumber theory

Given that a,b are integers such that $2a+3b=6$, I'm trying to prove:

i) $\frac{a}{3},\frac{b}{2}$ are integers

ii) gcd($\frac{a}{3},\frac{b}{2}$)=1

I know that, the solution of this linear diophantine equation is $a = -6 + 3n$ and $b = 6 – 2n$ where n is an integer.

From the solutions I can write:

$$\frac{a}{3}=-2+n\\\frac{b}{2}=3-n$$

Since n is an integer i) is proven. However, I have no idea how to move on with the second proof

Best Answer

We have that $$ 1=\frac{2a+3b}6=\frac a3+\frac b2$$ is a multiple of $\gcd(\frac a3,\frac b2)$.

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