1: Calculate the growth rate. Suppose: the growth rate is X.

Solution: 500+500x+(500+500x) x = 720 500+500x+500x squared = 720.

If each item is divided by 500, the square of 500X+1000x-220 = 0: the square of X +2X-0.44=0.

Use the formula to solve the quadratic equation of one variable: a= 1 b=2 c=-0.44.

X =-b√ b squared-4ac/2ax =-2 √ 2× 2-4x4/kloc-0 /×-0.44.

x = = 2 2.4/2 x 1 =-2+2.4/2 = 0.2 0.2× 100% = 20%

X2=-2-2.4 /2=-4.4/2=-2.2 is irrelevant.

The growth rate is 20%.

2. Calculate how many hectares there are from June to August * * * June: 500.

July: 500+500× 20% = 600 August: 600+600×20%=720.

500+600+720= 1820 hectares 3 months * * * Renovation of green belt 1820 hectares.