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# Math rate diffrentiation watch

1. the volume V of a sphere of radius 5cm is increasing at a rate of 10cm^3/s. Find the rate of increase of its surface area A at this instant.

2. (Original post by Revision99)
the volume V of a sphere of radius 5cm is increasing at a rate of 10cm^3/s. Find the rate of increase of its surface area A at this instant.

Chain rule, so .
Maybe you can find an equation for A in terms of V or use that .
3. (Original post by B_9710)
Chain rule, so .
Maybe you can find an equation for A in terms of V or use that .
Are you actually allowed to use A=πr² for this question?
4. (Original post by Dynamic_Vicz)
Are you actually allowed to use A=πr² for this question?
Yes you're allowed to use the area of a sphere which is .
Why would t you be allowed.

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