Answer:
-3
Step-by-step explanation:
[tex]6x^2+36x+54=0[/tex]
First, you can factor out a 6:
[tex]6(x^2+6x+9)=0[/tex]
Next, you can factor the quadratic:
[tex]6(x+3)^2=0[/tex]
Since the only value of x that could set this equation equal to 0 is -3, that is the answer. Hope this helps!