Locate a point C on the x-axis such that AC+BC is minimized. C=(_,0). The endpoints of AB are:

1) A(1,4) and B(4,-1)
2) A(-3,2) and B(-6,-4)
3) A(-2,3) and B(-4,0)
4) A(1,-3) and B(-1,1)

I really need help, I have no clue what I am doing. Thanks!:-)