Question

HELP!! :(

The area (A) of a circle is a function of its radius (r) and is given by the function A = f(r) = πr2. What is the domain of this function?

a: all positive real numbers
b: all real numbers
c: all positive real numbers including 0
d: all real numbers excluding fractions

Answer 1

If a function wouldn't represent area of a circle its domain would be all real numbers. For any number r we can calculate f(r)

But since radius of circle cannot be negative and it also doesnt make sense that it is 0 the answer would be all positive real numbers

Answer is a.