identify which is perfect square Trinomial (PST)or Not

1- x² – 12x + 36
2. y² + 4y – 4
3. m² – 11m + 25
4. a² + ab + b²
5.4x² – 40xy + 100y²

Answer: The correct answer is below.

1. PST

2. NOT

3. NOT

4. PST

5. PST