Here are the partial derivatives for the given functions.
i) For f(x,y)=x3+5xy+2y−2:
Step 1: Calculate the first partial derivatives.
fx(x,y)=∂x∂(x3+5xy+2y−2)=3x2+5y
fy(x,y)=∂y∂(x3+5xy+2y−2)=5x+2
Step 2: Calculate the second partial derivatives.
fxx(x,y)=∂x∂(3x2+5y)=6x
fxy(x,y)=∂y∂(3x2+5y)=5
fyy(x,y)=∂y∂(5x+2)=0
The derivatives for f(x,y)=x3+5xy+2y−2 are:
fx(x,y)=3x2+5y
fy(x,y)=5x+2
fxx(x,y)=6x
fxy(x,y)=5
fyy(x,y)=0
ii) For f(x,y)=8+cos2x−xy2:
Step 3: Calculate the first partial derivatives.
fx(x,y)=∂x∂(8+cos2x−xy2)=−2sin2x−y2
fy(x,y)=∂y∂(8+cos2x−xy2)=−2xy
Step 4: Calculate the second partial derivatives.
fxx(x,y)=∂x∂(−2sin2x−y2)=−4cos2x
fxy(x,y)=∂y∂(−2sin2x−y2)=−2y
fyy(x,y)=∂y∂(−2xy)=−2x
The derivatives for f(x,y)=8+cos2x−xy2 are:
fx(x,y)=−2sin2x−y2
fy(x,y)=−2xy
fxx(x,y)=−4cos2x
fxy(x,y)=−2y
fyy(x,y)=−2x
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