How does one go about solving this?

A skateboard rider starts from rest and accelerates at a constant +.50 m/s^2 for 8.4s. What is the riders displacement?

2 answers

X = (1/2) a t^2
a is the acceleration
t is the time
X is the displacement

The formula applies when the initial velocity is zero, as in this case.
thanks! I forgot the formula >.<