x1=1; x2=-1;
y1=-1; y2=0;
y=((x-1)*(y2-y1)+y1*(x2-x1))/(x2-x1);
subplot(1,2,1)
plot(x,y,'LineWidth',2)
hold on
text(1,2,'m1');
text(-1,0,'m2');
line([-5 5],[0 0],'color','black');
line([0 0],[-5 5],'color','black');
text(-0.5,-0.5,'O')
quiver(0,0,1,0,'k');
quiver(0,0,0,1,'k');
quiver(0,0,(x2-x1),(y2-y1),'LineWidth',3)
quiver(1,4,(x2-x1),(y2-y1),'LineWidth',3)
quiver(0,0,-(y2-y1),(x2-x1),'LineWidth',3)
quiver(1,4,-(y2-y1),(x2-x1),'LineWidth',3)