Quick vector calc question need verifying

[HmBe]

Homework Statement

Homework Equations

The Attempt at a Solution

For the acceleration I got du/dt=0, and the rest ends up equalling (-3x)i + (-3y)j, so this is the acceleration.

A mate of mine got something slightly different, but I'm pretty sure mine is right - can anyone confirm this?

Cheers.

 

[HmBe]

Anyone?