7. Take the wall as one side, and the other three sides are surrounded by bamboo fences with a length of 33 meters to form a rectangular flower bed with an area of 130 square meters. Known wall length15m. What is the length and width of the flower bed to make the bamboo fence just right?

The length and width of the bamboo fence are x and y respectively, and the length of one side of the bamboo fence shall not exceed 15m.

XY= 130

2X+Y=33

x(33-2x)= 130

Then X= 10.

Y= 13

So the length is 13 m and the width is 10 m.

9. A factory produced 200 machines in 1 month and 662 machines in the first quarter. What is the average growth rate in February and March?

Let the average growth rate in February and March be x.

200+200( 1+x)+200( 1+x)^2=662，

So x 2+3x+3 = 3.3 1,

So x 2+3x-0.3 1 = 0,

So (x-0. 1)(x+3. 1)=0,

So x=0. 1 or x=-3. 1 (obviously irrelevant, omitted)

So the average growth rate in February and March is 10%.