If you're referring to the different sets of real numbers, it's the ones that you could try to do subtraction and not get an answer that still in that set.
For example, natural numbers (aka 1, 2, 3, 4, ...) are not, because 7 - 11 = -4 and -4 is not a natural number.
Also, whole numbers (aka 0, 1, 2, 3, 4, ...) has the same issue.
Basically any set of real numbers that doesn't include negative numbers will have this issue.
The answer to this question would be 6
Step-by-step explanation:
1) Perimeter = 2(l + w)
Perimeter = 2(94 + 64)
Perimeter= 2(158) = 361 cm
2) Fabric required = Area
Area = l × b
Area = 94 × 64
Area = 6016 cm²
Answer:

Step-by-step explanation:
Given:
Center of circle is at (5, -4).
A point on the circle is 
Equation of a circle with center
and radius 'r' is given as:

Here, 
Radius of a circle is equal to the distance of point on the circle from the center of the circle and is given using the distance formula for square of the distance as:
Using distance formula for the points (5, -4) and (-3, 2), we get

Therefore, the equation of the circle is:

Now, rewriting it in the form asked in the question, we get
