[SOLVED] Equations of Motion

This is just something which has been bothering me and want your expertise on it.

Initial Velocity = 0

Acceleration = 1

Distance = 3

Find the time taken to cover that distance.

So generally I would use the second equation of motion to get an answer

t=2.45s

But why don't I get the same answer when I try to solve it in this way...

$\displaystyle a=\frac{v}{t}$ and $\displaystyle v=\frac{d}{t}$

Thus,

$\displaystyle a=\frac{d}{t}/t$

$\displaystyle a=\frac{d}{t^2}$

$\displaystyle 1=\frac{3}{t^2}$

$\displaystyle t=1.73s$

What am I doing wrong? Why don't the answers match?