Math problems, you can come, don t talk nonsense, 3 questions

Calculate yourself, there is a square karma, pay attention, "* is multiplied by the solution: let the average monthly growth rate of the plant's output in June and July be x."

500 * 1+x）²=648

Answer:.. Solution: Let's say the monthly growth rate is x

25 * 1+x）² =91

Answer:.. Solution: Suppose the average annual depreciation rate of the car in the second and third years is x12* (

Answer:..

(1) In May, it is 500 (1-10%)=450, and the growth rate is x

Then June is 450 (1+x).

July is 450 (1+x) (1+x) = 648

1+x)²=648/450=

1+x=x=20%

So the growth rate is 20%.

2) 250,000 in January, 25(1+x) in February and 25(1+x) in March

So 25+25(1+x) +25(1+x) 2=91(5x-1)(5x+16)=0 So x=1 5(3) solution: Let the car be the first.

2. The average depreciation rate for the third year is x.

12（1－20%）（1－x）^2＝

x1, x2 rounded).

A: The average depreciation rate is 10%.

1) 648 500 (1 10) [500 (1 10)]

2) Let the growth rate be x, 25 (1 1 x 1 2x x 2) 91 solution.

3) Let the depreciation rate x, 12 (1 20 ) (1 x) 2 solution.

In May it is 500 (1-10%)=450

Let the growth rate be x

Then June is 450 (1+x).

July is 450 (1+x) (1+x) = 648

1+x)²=648/450=

1+x=x=20%

So the growth rate is 20%.

1. Let the average growth rate be x, and the output in May can be seen to be 450 tons according to the question, so 450 (1 + x) 2 = 648, and the solution is x = 20% 2

25+25(1+x)+25(1+x) 2=91, (5x+16)(5x-1)=0, and x=20% is solved

3. From the question, it can be seen that the value of the car in the first year: 12 * (10,000, let the average annual depreciation rate be x, then:

Solution: x=

1.2000 (5*120+70*2)* Meets requirements.

2.According to the question, the total score of the 6 students is 6*85=510, the total score of the top 4 is 4*89=356, that is, the total score of the last two students is 510-356=154, and the total score of the last 4 students is 4*82=328, so the total score of the 3rd and 4th places is 328-154=174, so the average score of the 3rd and 4th places is 174 2=87

3.Let the height of the original cuboid be h decimeters, then the width is also h decimeters, and the length is 3h decimeters, so that the height of the small cuboid is h 2 decimeters, the width is h decimeters, and the length is h decimeters, and the surface area of a small cuboid is 4 h 2 h + 2 h h 4h 4h The surface area of six small cuboids and 864 6 4h 24h h 6 The original cuboid volume is h h 3h 3 6 648 square decimeters

1. Set the original x book, then.

x* (so x=1200 copies.)

2. Set the purchase price to be x yuan, then.

x*(1+so x=200 yuan.)

3 set the total length x meters, then.

x*4/9+300+x*

So x = 1440 meters.