I would make a table and plug values(or just plug in x values) in to figure out the equation's graph: (plug in values that will make it easy for you since you have a √)
f(x) = 3(√x)
x = 0
f(0) = 3(0) = 0 ------> (0 , 0)
x = 1
f(1) = 3(√1) = 3(1) = 3 ------> (1 , 3)
x = 4
f(4) = 3(√4) = 3(2) = 6 ------> (4 , 6)
Now that you have found some points, find a graph/line that goes through these points