Question 616943
As you say, area of a rectangle is length times width. So we want to express the given area as the product of a length and width. So let's factor it:
Area = {{{-8y^9-32z^4+56x^2 = 8(-y^9-4z^4+7x^2)}}}<br>
Since {{{-y^9-4z^4+7x^2}}} <i>seems</i> bigger, let's call that the length, making the 8 the width. So the dimensions are
length = {{{-y^9-4z^4+7x^2}}} meters
width  = 8 meters