What does it mean if something is a common factor of an expression?

Common factor is a number (or expression) that two or more numbers (expressions) can be divided by.

For example: numbers 3, 6, 12. Their common factor is 3. Each of these numbers can be divided by 3. So, 3 is the common factor here.

Another example: expression 5x²+10xy+15xy². Each of the terms in this expression can be divided by 5x. So, 5x is common factor of this expression.

Hope that helps,

Inga