# Differentiating volume of a cylinder

1. May 22, 2006

### rachael

1. differentiate the volume of a cylinder with v respect to h

my working out:
v= πr^2h
dV\dh= 2πr

n da answer is not right
how do i make da "h" remains in da equation?
thank you

2. May 22, 2006

### arunbg

Hint:Note that r is a constant

3. May 22, 2006

### rachael

i am not sure what you mean though

do u mean that dV\dh= πh??? instead of 2πr

4. May 22, 2006

### J77

What you've done is differentiate with respect to h and then with respect to r (or r then h) to get at $$2\pi r$$.

You can leave the r alone and just diff. w.r.t. h

5. May 22, 2006

### HallsofIvy

If "A" is a constant and v(h)= Ah, what is dv/dh?

If $v(h)= \pi r^2h$, what is the constant "A"?

6. May 23, 2006

### rachael

do i apply the product rule to find dv/dh?

7. May 23, 2006

No,