1. solution: let the triangle intersecting the coordinates be y low.

3y× half = 6

y = 4

Then: the intersection with the y axis may be (0,4) (0,4).

Bring the two points into the analytical formula y=kx+b, and the analytical formula is y= minus three quarters x+4 or y= three quarters x+(-4).

2. Set A- A X, then B- A (15-x), A- B (16-x) and B-B (x-3), and then 3.

Let y be the total cost, then y = 500 x+300 (15-x)+400 (16-x)+600 (x-3) = 400 x+9100, and when x=3, y

3. Scheme 1: y=5x+60 Scheme 2: y = 73.6+4.6x.

5x+60 = 73.6+4.6x 5x+60 > 73.6+4.6x 5x+60 < 73.6+4.6x

x = 34 x>34 x