Question

Which of the following constants can be added to x2 + x to form a perfect square trinomial? a.1/9 b.4/9 c.4 1/9

Answer 1

You can add 4/9. 

A simple trick is to look at the numerator and denominator separately, if they're both perfect squares then you're good (4, 2^2, check. 9, 3^2, check.)