The volume of a rectangular prism can be expressed as a function of a single variable x if it is a square prism or a cube.
For a rectangular prism with sides w, l and h the volume is V = w*h*l. If w = l = h = x the volume is V = x^3.
The volume V of a prism with equal sides x is V = x^3.
Let the rectangular prism have sides in ratio a:b:c so that the sides measure ax, bx and cx the the volume (V) of the prism can be expressed in terms of x as: V=ax*bx*cx or V = a.b.c.x^3
Volume of the rectangular prism having sides in ratio a:b:c and lengths of sides as ax, bx, cx is a.b.c.x^3