syms x y
k = 2;
if k == 1
    f1 = @(x)1/4*(x.^2 - log(x.^2) - 1);
else
    f1 = @(x)1/2*((1-x.^(1-k))./(1-k) - (1-x.^(1+k))./(1+k));
end
x1 = [0:0.01:1];
plot(x1,f1(x1))