In the equation a² + bx + c, for the equation to be a perfect square, c must be equal to (b/2)²
---------------------------------------------------------------------------------------
The missing constant = [tex]( \dfrac{14}{2} )^2[/tex]
The missing constant = [tex](7)^2[/tex]
The missing constant = [tex]49[/tex]
----------------------------
Answer: 49
----------------------------