Chapter 3.4, Problem 75E

Let z(x, y) = -3x² + 8y² where x = 4s + 2t & y = −5s - 8t. Calculate მ მ მე მყ მეთ მყ & by first finding and using the chain rule. მე Ət მs’მვ’მt It

Find the differential of the function f(x,y) = 3xe² at the point (3, 4) using Ax = 0.3 and Ay = −0.2 dz = Now find Az and compare it to your answer above Az = Hint: If entering a decimal, round to at least 5 places

Let z(x, y) = xºy where x = t³ & y = tº. dz dx dy Calculate by first finding & and using the chain rule. dt dt dt

Let x(x, y) = −6e² sin(y) where x = ƒ³ & y = 5πt. dz dx dy Calculate by first finding & and using the chain rule. dt dt dt

Calculate sin(10y(2)) where y is the solution of 4.149 12x²y" + 23xy' + 2y : - x such that y(1) = 1, y′(1) = 0, by finding two solutions to the homogeneous equation of the form x and then using the method of variation of parameters. -0.842 0.035 -0.708 -0.109 0.226 0.092 -0.377 -0.274

A New Heating System A homeowner wants to replace their old heating system. Energy is measured in kilowatt-hours (kWh). It takes about 11,700 kWh of energy to heat the house for the winter. The current heating system uses natural gas and is 60% efficient, which means that for every 100 kWh of natural gas it uses, it produces 60 kWh of heat. With the homeowner's current system, it costs $975 to heat the house. Assume that natural gas costs $0.05/kWh and electricity costs $0.21/kWh. The homeowner also has an air conditioner that uses 2,500 kWh of electricity per year and produces 290 kWh of cooling for every 100 kWh it uses. They also have a water heater that uses 4,300 kWh of electricity per year and produces 90 kWh of heat for every 100 kWh it uses. These systems could also be replaced if there is a cheaper option, but it isn't necessary. Here are three other types of heating systems the homeowner could replace their current system with: • A new furnace which also runs on natural gas…

Find a unit normal vector to the surface f(x, y, z) = 0 at the point P(-3,4, -32) for the function f(x, y, z) = In -4x -5y- Please write your answer as a vector (a, b, c) with a negative z component, and show your answer accurate to 4 decimal places

Find the differential of the function f(x, y) = 2x² - 2xy – 5y² at the point (-6, -5) using Ax = 0.3 and Ay = 0.05. dz = Now find Az and compare it to your answer above Ax= Hint: If entering a decimal, round to at least 5 places

Find the differential of the function f(x, y) = −8x√y at the point (1,3) using Ax = 0.25 and Ay = -0.15. dz Now find Az and compare it to your answer above Az = Hint: If entering a decimal, round to at least 5 places