Vector motion?

Question

The position of a particle as a function of time is given by:
r (vector)=(5i +4j)t^2 m, where t is in seconds

What is the particle's distance from the origin at t = 0, 2, and 5 s?

Answer 1

The distance from the origin is sqrt(x^2+y^2) where x=4t^2 and y=5t^2 so for this problem
distance= sqrt(41) t^2

Answer 2

t=0 position is where i and j cross (center).

t=2 position is R=2(5i+4j)m

t=5 position is R=5(5i+4j)m