Homework #2 Problem #2

[Regina Phalange]

I am stuck trying to solve problem #2. I keep getting a quadratic equation that can't be solved. Can somebody please explain how to solve it?

[Taeho Kim]

It was my mistake, Regina.
There is a typo in the problem.
We need to use {0,1,3,a,b} instead of {0,1,2,a,b}.

My apology for the time loss.