∴m=2.
Therefore, the value of m is 2;
(2) Points A and B are perpendicular to the X axis, and the vertical feet are points E and D respectively.
From the meaning of the question, AE=6, OE= 1,
∵BD⊥x axis, AE⊥x axis,
∴AE∥BD，
∴△CBD∽△CAE,∴CB/CA =BD/AE，
∵AB=2BC,∴ CB/CA= 1/3，
∴BD=2.
That is, the ordinate of point B is 2.
When y=2 and x=-3, we know that the straight line AB is y=2x+8.
∴C(-4,0).
Hope to adopt, thank you!