What is the correct way to do these problems?

I need help figuring out the following questions please! I also need it asap!

9.5.1 Evaluate dz using the given information. z=6x2 +8xy+7y2; x=4, y= 1, dx=0.03, dy= 0.02 dz = E (Type an integer or a decimal.) 9.5.3 Evaluate dz using the given information. y2+3x_ y2-7x' dzmlj (Do not round until the nal answer. Then round to four decimal places as needed..) z= x=5,y= -5,dx=0.06,dy=0.03 9.5.5 Evaluate dw using the given information. _ 8x2 + 33!2 w 2+2 (1me (Do not round until the nal answer. Then round to four decimal places as needed..) ;x= -6,y=4, z=5, dx=0.04, dy= -0.07, dz=0.08 Bus Econ 9.5.15 Approximate the volume of aluminum needed for a beverage can of radius 2.5 cm and height 11 cm. Assume the walls of the can are 0.06 cm thick. The volume of aluminum needed is D cm3. (Round to the nearest hundredth as needed.)