x = [-0.5:1/1000:0.5];
y1 = x.^2;
y2 = x.^3;
y3 = x.^4
y4 = x.^5;
y5 = x.^5;


plot(x,y1,'b',x,y2,'r',x,y3,'g',x,y4,'y'); hold on; 
plot(x,y5,'m',x,0,'c'); hold off