y=( 10+0.5x)(2000﹣6x)
That is: y =-3x2+940x+20000 (1≤ x ≤1/kloc-0, where x is an integer);
(2) From the meaning of the question:-3x2+940x+20000-10× 2000-340x = 22500.
Solve the equation: x 1 =50, x 2 =150 (irrelevant, omitted),
∴ Li Jing needs to store these mushrooms for 50 days to make a profit of 2,250 yuan;
(3) Let the profit be w, which is derived from the meaning in the question:
w=﹣3x 2 +940x+20000﹣ 10×2000﹣340x=﹣3(x﹣ 100)2+30000,
∵a=﹣3<; 0,
∴ Parabolic opening direction downward,
∴x= 100,w max =30000,
100 days < 1 10 days,
Store 100 days, and sell these mushrooms, and the maximum profit can be 30,000 yuan.