Answer:
I hope it's helpful.
Step-by-step explanation:
In mathematics, an extraneous solution (or spurious solution) is a solution, such as that to an equation, that emerges from the process of solving the problem but is not a valid solution to the problem.
the expression is 27a^3 or (3a)^3
The choice third ; a=9 , c= 18
when the radicand is negative