Question

A(r) is a function that gives the area of a circle with the radius r. It can be written in equation form as A(r)=3.14r^2. what is the value of A(4)?

Answer 1

Plug "4" into the function where you see "r".

\[A(4) = \pi(4)^2\]

A(4) simply means "The area when 'r=4'".
From here, just solve the equation.