If each side of a square is increased by x units then its perimeter is increased by how many units?

Let's note the length of the side of the square as
l.

As we know, the lengths of the sides of the square are
equal.

The perimeter of the square is the sum of the lengths of the
sides. Since the lengths are equal, we'll get:

P1 =
4*l

If each side is increased by x units, we'll have the new
perimeter;

P2 = (l+x) + (l+x) + (l+x) +
(l+x)

P2 = 4(l+x)

Now, the increasing
of P2 over P1 is:

P2 - P1 = 4(l+x) -
4l

We'll remove the brackets and we'll
get:

P2 - P1 = 4l + 4x - 4l

We'll
eliminate like terms:

P2 - P1 =
4x

The original perimeter is 4x units
smaller than the new one.