syms x;
f = @(x) (1+x^2)^(-1);

f2 = diff(f,x,3);
f4 = diff(f,x,5);
f6 = diff(f,x,7);
f8 = diff(f,x,9);

z = linspace(-1,1,100);
y2 = zeros(1,100);
y4 = zeros(1,100);
y6 = zeros(1,100);
y8 = zeros(1,100);

for i=1:100
    y2(i) = subs(f2,z(i));
    y4(i) = subs(f4,z(i));
    y6(i) = subs(f6,z(i));
    y8(i) = subs(f8,z(i));
end

subplot(2,2,1)
plot(z,y2)
title('f^{(2)}')
subplot(2,2,2)
plot(z,y4)
title('f^{(4)}')
subplot(2,2,3)
plot(z,y6)
title('f^{(6)}')
subplot(2,2,4)
plot(z,y8)
title('f^{(8)}')
    