50X( 1-30%)( 1+x)( 1+x+5%)= 48.3

50×0.7×( 1+x)( 1.05+x)= 48.3

35×( 1+x)( 1.05+x)= 48.3

( 1+x)( 1.05+x)= 48.3÷35

x？ +2.05x+ 1.05= 1.38

x？ +2.05x-0.33=0

100x？ +205x-33=0

(20x-3)(5x+ 1 1)=0

x 1= 15%，x2=-5/ 1 1

X2 =-5/ 1 1 does not meet the meaning of the question, so it is omitted.

So the growth rate in April is 15%, so the growth rate in May is 15%+5% = 20.

2. Solution:

(1) set: this village has built x hectares of vegetable greenhouses a year. The cost of purchasing sprinkler irrigation equipment is 9000x^2 yuan.

According to the meaning of the question: 75000 x-(27000 x+9000 x 2) = 60000.

Tidy up and simplify: 3x 2- 16x+20 = 0 solution:

X= 10/3 or x=2.

In a year's time, this village has built 10/3 or 2 hectares of vegetable greenhouses.

(2) The benefit of building a 3-hectare greenhouse = 75,000× 3-(27,000× 3+9,000 3 2) = 63,000 yuan.

The benefit of building a 3-hectare greenhouse is 63,000 yuan.

(3) Suppose: the maximum income is Y yuan, according to the meaning of the question: Y = 75000x-(27000x+9000x 2).

∴y=-9000x^2+48000x

When x=4800/(2×900)=8/3 (hectare), y is the largest.

∴: It is not that the larger the greenhouse area, the greater the income. When the greenhouse area is 8/3 hectares, the maximum income is 64 thousand yuan.