20 1 1 The math problem of Chongqing senior high school entrance examination is as follows: the image of linear function y=kx+b and inverse proportional function in plane rectangular coordinate system xOy. (1)① Make AF⊥X axis when crossing point A;

OA = 5，Sina OE = 4/5；

∴AF=4, OF=3, which is a (-3,4).

And ∵A versus inverse proportional function y=m/x,

∴, 4=m/(-3), that is, m=- 12, then the inverse proportional function y =-12/x.

②∫B(6, n) is on the inverse proportional function y=- 12/x,

∴n=- 12/6=-2, that is, B(6, -2)

And the straight line y = ∵A, b in kx+B.

∴ Equations: -2=6k+b

4=-3k+b

Solution: k=-2/3, b=2, that is, y=-2/3x+2.

(2) When the straight line AB intersects the X axis at point C, let point C (x, 0) be set.

If point c is substituted into the straight line y=-2/3x+2, then x=3.

S△AOC = S△AFC—S△AFO = 1/2cf×AF- 1/2of×AF = 1/2AF(CF-OF)= 1/2AF×OC = 1/2×4×3 = 6

That is, S△AOC=6.