1 The area Aof a disk of radius r is given by the formulaA= r². Assume that the area increases at a rate of 5ft²/sec. Find the rate with which the radius increases at the moment when the diameter d=16ft. (Enter your answer correct to at least five decimal places, you may use the value ofprovided by your calculator, or alternatively use 3.1415926535 )

2. Given 2x²y - 2y³= 5x - 4 , useimplicit differentiation to find the derivative y'=dy/dxand evaluateitat the point (x,y)=(2,1).

3. As a snowball melts,its area Adecreases at the rate 3cm²/minute.Find the rate with which it radius decreases, when the radius r=4cm.Use that the surface area of a sphere is given by the formula A=4r² (where isapproximately3.1415926535). Enter your answer as a number only, correct to at least four decimal places, no sign.