An equation that is true for all real numbers for which both sides are defined is called a(n)

It called identity. Identity equations are conditions that are genuine regardless of what esteem is connected to for the variable. On the off chance that you rearrange a personality condition. 
An identity is a balance that remains constant paying little respect to the qualities decided for its variables.They are utilized as a part of streamlining or reworking polynomial math articulations. By definition, the two sides of a character are tradable, so we can supplant one with the other whenever.

B12/23 is your answer