(1) the straight line l 1: Y 1 = 2x+3 intersects with the straight line l2: Y2 = KX- 1 at point A, and the abscissa is-1, and the straight line l 1 intersects with the X axis at point B.

The coordinates of point A are a (- 1, y), which are obtained by substituting l 1 and l2 respectively.

y=2x+3=-2+3= 1

y = kx- 1 =-k- 1 = 1，k=-2

∴ The coordinate of point A is a (- 1, 1), and the analytical formula of line l2 is y2 =-2x- 1.

(2) when y 1 = 2x+3 = 0, x =- 1.5, and the coordinate of point b is b (-1.5,0).

When y2 =-2x- 1 and x=0, y2 =- 1, and the coordinate of point c is C(0,-1).

When Y2 =-2x- 1 = 0, X =-0.5, and the straight line l2 intersects the x axis at e (-0.5,0),

BE=|- 1.5|-|-0.5|= 1

S△ABC= S△ABE+ S△CBE, the height of △ABE is h 1= 1, and the height of △CBE is H2 = |- 1 | = 1.

S△ABE=BE？ h 1/2+= 1× 1/2 = 1/2，

S△CBE= BE？ h 1/2+= 1× 1/2 = 1/2，

∴S△ABC= 1。