Answer:
See below
Explanation:
An invalid solution.
When you use the quadratic formula, for example, to solve for 't', time, you will often find one of the values of 't' to be NEGATIVE value for time.....this would be an extraneous solution.
Sometimes when working with LOG equations you may fin an answer which is negative.....you cannot have a LOG of a negative number...THAT solution would be EXTRANEOUS
ETC
SO, always check your answers to see if they 'work' for your problem.