Differentiating volume of a cylinder

[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?
could some one please help me?
thank you

 

[arunbg]

Hint:Note that r is a constant

 

[rachael]

i am not sure what you mean though

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

 

[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

 

[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"?

 

[rachael]

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

 

[arunbg]

No,
Read Hallsofivy's post carefully.