posted by Grace on .
A rectangular field is to be fenced off with 120 m of fencing materials. the length of the field is x. express the area in square meters of the field as a function of x.
nice try, but you're mixing things up. Why do you say 120 m^3? m^3 is volume, not are or length! And why multiply the perimeter by the length, anyway?
Just take a step back and work things out.
The area is length * width
The 120m of fencing reaches around the field -- that is the perimeter.
If the perimeter is 120, that means that
So, if the length is x,
width = 60-x
That means that the area is
and that is in m^2: meters * meters