I have to prove that a/b and a/c then a/ (3b-7c), where a, b, and c are integers. I know this is true but I need help with the proof.

Do I assume a does not /(3b-7c)?

I am so lost....please help

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- Mar 23rd 2010, 12:13 PMmath61688Prove a/b and a/c then a/ (3b-7c)
I have to prove that a/b and a/c then a/ (3b-7c), where a, b, and c are integers. I know this is true but I need help with the proof.

Do I assume a does not /(3b-7c)?

I am so lost....please help - Mar 23rd 2010, 02:18 PMemakarov
I assume that a/b means "a divides b". A vertical bar usually denotes "divides".

If a divides b, then b = k * a for some integer k, and similarly for c. Now, both b and c are expressed through a, so 3b - 7c can also be expressed through a. - Mar 23rd 2010, 05:20 PMmath61688
Thanks!