can anyone help with this?

Answer:
46
Step-by-step explanation:
The complete square starting with [tex]x^2+14x[/tex] would be [tex]x^2+14x+49[/tex], since the square would be [tex](x+7)^2[/tex]. To make this square perfect, then, you would need to add 46 to make 49 with the 3. Hope this helps!