Respuesta :
The perfect square trinomial will be 16x² + 24xy + 9y². Expression 3 is correct. Ax + By + Cz are trinomials.
What are trinomials?
A mathematical expression with three terms or three monomials is called a trinomial. Polynomials having only three terms are known as trinomials.
The third expression seems to be the perfect square let's check it.
[tex]\rm 16x^2 + 24xy + 9y^2 \\\\ (4x)^2+ (2 \times 4x + 3y) + (3y)^2 \\\\ (4x + 3y)^2[/tex]
Hence the expression 3 is the perfect square.
To learn more about the trinomials refer to the link;
https://brainly.in/question/8498839
