Question

the length of a rectangle is 4 units greater than its width, and the area of the rectangle can be expressed by the eqaution y = x2 + 4x. what is a reasonable domain for this function?

Answer 1

x>0

Explanation:

Since we are dealing with measurements, we do not want negative numbers. This gives us the domain x≥0.

However, we also cannot include 0 in the domain. This is because the domain, x, represents the width; since the figure is a rectangle and has 4 sides, it will have a width. If the width was 0, the rectangle would have no width and would lose its shape.

This gives us the domain x > 0.

Answer 2

When talking about object measurements, we usually require they be positive.

A suitable domain is x > 0.
(and somewhat less than any substantial fraction of the Earth's dimensions. The numerical value will depend on the chosen units.)