The distance, d (in metres), which an object travels. is given by the equation $\displaystyle d=ut-8t^2 $ where u is the initial velocity (in metres per second) and t is the time in seconds it has been travelling. Show that there is only one value for t when $\displaystyle u^2 =32d$

I'm having real trouble solving this equation for t using any algebraic method that I've learnt for quadratic equations.

I can't figure out how to put it into the quadratic formula simply for the fact that i can't get any of the variables by themself on either side of the equation to set as x.

The steps I've tried so far in order to rearrange for t are:

$\displaystyle d=ut-8t^2$

add 8t^2 to both sides

$\displaystyle d+8t^2=ut$

divide both sides by t

$\displaystyle d/t+8t=u$

take d/t away from both sides

$\displaystyle 8t=u-d/t$

and here is where i lose track, because i figure out that i can't rearrange for t at all. i've considered converting d/t into V (final velocity) but i can't see that helping much.

Any suggestions would be much appreciated.