% problem 1

n = 1:1000; sqrt(16*sum(1./((2*n-1).^2.*(2*n+1).^2)) +8)

% problem 2

x = [ 2 5 1 6]

x = x + 16
x([1 3]) = x([1 3]) + 3
x = sqrt(x)
x = x .^ 2

% problem 3

x = linspace(0,4,100);
plot(x,x,'b')
hold on
plot(x,x.^3,'r')
plot(x,exp(x),'g')
plot(x,exp(x.^2),'k')

xlabel('x')

% restrict the axis using this
% [ xmin xmax ymin ymax ]
axis( [ min(x) max(x) 0 100 ] )

% add a legend 
% note: -1 puts it outside the plot area
legend(-1,'x','x^3','e^x', 'e^x^2')