Answer and Explanation
Your Answer is
Correct Answer is K
Explanation
To make the original formula unsolvable, then a2+1=0, then a=i
20. One of the following values for a makes the expression 
undefined. Which one?
20. One of the following values for a makes the expression undefined. Which one?
Your Answer is
Correct Answer is K
Explanation
To make the original formula unsolvable, then a2+1=0, then a=i