Concept:To differentiate a function of the form (x+x1)2, first expand the square, then apply the power rule of differentiation: dxdxn=nxn−1 for each term, and the derivative of a constant is zero.Explanation:Step 1: Expand the given function:f(x)=(x+x1)2=x2+2⋅x⋅x1+x21=x2+2+x−2.Step 2: Differentiate term by term with respect to x:dxd(x2)=2xdxd(2)=0dxd(x−2)=−2x−3=−x32Step 3: Combine the results:f′(x)=2x−x32=2(x−x31).Answer:2(x−x31) which corresponds to option C.