Answer:
9 or -6
Step-by-step explanation:
To solve, I would suggest factoring.
You need to find two numbers which can be multiplied for 54 and also combined in some way to get 3. In this case, 9 and 6 are perfect.
[tex]x^2-3x-54=0\\(x-9)(x+6)=0[/tex]
Next, you can set both of your terms equal to zero to find your possible solutions.
[tex]x-9=0\\x=9\\[/tex]
or
[tex]x+6=0\\x=-6[/tex]
