# elementary math

posted by
**anna**
.

i did use my poof to prove. im not sure im doing right.

here is exercises:

'Suppose a,b,c are integers if a|b and a|c, then a|(b+c).'

my answer:

Proof. Suppose a|b ans a|c.

By Definition of divisibility. we know a|b means there is an integer x with b= ax.

Likewise, a|c means there is an integer y for which c= ay

Thus b+c=(ax+ay)= a(x+y)

therefore a|(b+c).