Question

What must be true of two rational expressions before they can be added? They must have common numerators. They must be of the same degree. They must have the same variables. The must have common denominators.

Answer 1

They must have common denominators

Explanation:

Answer 2

They must have common denominators.

EXPLANATION

Given any two rational expressions say,

`(p)/(n) \: \: and \: \: (q)/(m)`

where m,n,p,q are integers, and n,m≠0

We can only add these two rational expressions if they have a common denominator.

That is why we find LCD to be mn.

Then

`(p)/(n) \: \: + \: \: (q)/(m) = (mp + nq)/(mn)`

The last choice is correct.