The diagram below shows a solid with volume V, obtained from a cube with edge

a > 1 when a smaller cube with edge 1/a is removed.

sorry for the image but there is not...so imagine a solid with an edge missing...so a small solid is missing on 1 edge..

Let x=a − 1/a

-Find V in terms of x

Hence or otherwise,show that the only value of a for whichV= 4x is a= 1+ √5 devided by 2..