Question

The area A of a circle is a function with respect to its radius r: A = pi r^2.

(dA)/(dr) =

Answer 1

dA=2pi*r

Answer 2

that's the equation so I just need to plug in the numbers,
right?

Answer 3

you don't have to plug in anything if this is the complete text

Answer 4

what is the star between pi and r represent?

Answer 5

times

Answer 6

Remember that pi is just a number and the radius, r, is your independent variable. So you take the derivative using the power rule. So, A'= 2*(pi)r^(2-1), or just 2(pi)r.

Answer 7

\[A=\pi r^2\]\[\frac{dA}{dt}=\frac d{dt}(\pi r^2)=\pi\frac d{dt}r^2=\pi(2r)=2\pi r\]

Answer 8

right, power rule

Answer 9

that what I got ok thanks

Answer 10

you're welcome :D