How Do You Compute the GCD of Three Numbers Using Pairwise GCD?

[bobby2k]

Homework Statement

Show that in order to find common denominator of a,b,c, you can first find the gcd to a and b called d.
Then gcd(a,b,c)= gcd(d,c)

Homework Equations

The Attempt at a Solution

I know that we atleast must have that gcd(a,b,c) divides d, can I use that?

 

[haruspex]

Homework Statement

Show that in order to find common denominator of a,b,c, you can first find the gcd to a and b called d.
Then gcd(a,b,c)= gcd(d,c)

Homework Equations

The Attempt at a Solution

I know that we atleast must have that gcd(a,b,c) divides d, can I use that?

Yes, that will help you show that gcd(a,b,c) divides gcd(c,d). Then you have to show the converse.