Question

When is it necessary to apply the Distributive Property?

Answer 1

It is necessary when you are getting into multiplying from the outside of parenthesis and multiplying variables inside of parenthesis.
ex: 5(3 + 3x)
5 * 3 = 15
5 * 3x = 15x
so final set up would be 15 + 15x  

Answer 2

The distributive property is necessary when you are asked to simplify and distributive property is possible.