Velocity and Acc Question HSC 1997 (1 Viewer)

[Drewk]

http://snag.gy/pLUT9.jpg
Trying this past hsc question using 1/2v^2
because we r given v i squared both sides then got 2xe^-x^4
then i would differentiate and mul by 1/2 but i don't think that gets me to the answer
Please help

 

[Samir97]

When you square it the power becomes -2x^2 not x^4 because two powers would simply multiply so 2 x -x^2 is -2x^2

 

[HeroicPandas]

factorise and ur done

 

[Samir97]