# How do you graph f(x)=3-sqrt(x-2)?

You first need to check which $x$ values you can use. The argument of your square root must be bigger or equal to zero (you cannot have a negative argument). So you need:
$x - 2 \ge 0$
i.e. $x \ge 2$
To plot your function we try $x$ values that gives you an "easy" square root to evaluate, such as $2 , 3 , 6 , 11 , 18 , 27. . .$: