(1) Three kinds of vegetables, cucumber, kidney bean and Chinese cabbage, are planted in a rectangular field of 45cm in length and 20m in width. The planting area ratio of cucumber, kidney bean and Chinese cabbage is 7:5:8. How many square meters are planted for each of the three crops? (2) the school playground is 100m in length and 60m in width. How many cm should be drawn for each length and width on a drawing scale of 1 / 2000? (3) a kind of soybean can squeeze 5kg oil per 20kg, How many kilos of this kind of soybean is needed to squeeze 90 kilos of oil

(1) Three kinds of vegetables, cucumber, kidney bean and Chinese cabbage, are planted in a rectangular field of 45cm in length and 20m in width. The planting area ratio of cucumber, kidney bean and Chinese cabbage is 7:5:8. How many square meters are planted for each of the three crops? (2) the school playground is 100m in length and 60m in width. How many cm should be drawn for each length and width on a drawing scale of 1 / 2000? (3) a kind of soybean can squeeze 5kg oil per 20kg, How many kilos of this kind of soybean is needed to squeeze 90 kilos of oil

(1) The total area of the rectangle is
0.45×20=9m²
When the planting area ratio of cucumber, kidney bean and Chinese cabbage is 7:5:8, the proportion of cucumber, kidney bean and Chinese cabbage is 0
Cucumber 7 / (7 + 5 + 8) = 7 / 20
Kidney bean 5 / (7 + 5 + 8) = 5 / 20 = 1 / 4
Cabbage 8 / (7 + 5 + 8) = 8 / 20 = 2 / 5
The planting areas were
Cucumber 9 × 7 / 20 = 3.15 M & sup2;
9 × 1 / 4 = 2.25 M & sup 2;
Chinese cabbage 9 × 2 / 5 = 3.6m & sup2;
(2) The scale is 1 / 2000
The length of the drawing is 100 × 1 / 2000 = 0.05m = 5cm
The width on the drawing is 60 × 1 / 2000 = 0.03m = 3cm
(3) If x kg of this soybean is needed, then
20∶5=x∶90
X = 360 kg

Ask three practical questions, just one formula,
1. The average house price of a residential area is 4800 yuan per square meter, which has increased by 1 / 8. Now the average price is 5400 yuan per square meter
To buy a house, you need to pay the deed tax of 3 / 200 of the total house price. How much should you pay for a 100 square meter house at the current price? 548100 yuan
2. Xiaoming and Xiaojun ride from place a to place B. when Xiaoming rides to 3 / 4 of the whole journey, Xiaojun just rides to 4 / 5 of the whole journey. At this time, the distance between them is 400 meters. How many meters is the whole journey? 8000 meters
3. For a batch of 720 tons of fruits, 3 / 8 of them should be transported in the first day, and how many tons should be transported in the second day, so that the remaining 1 / 3? 210 tons of fruits can be transported

1、5400*100*（1+3/200）=548100
2、400/（4/5-3/4）=8000
3、720-720*3/8-720/3=210

④ Dao application problem is the circumference of the circle (there should be a circle formula and formula and process, not only the answer) good bonus
(1) The radius of the earth's equator is about 6378 kilometers. How many kilometers is it to walk around the equator
(2) Coil with copper wire, coil radius is 1.5cm, how much copper wire is needed for 100 turns?
(3) 628 mm long thin steel wire is just wound 10 times on a round iron bar. How many square millimeters is the cross section of this round iron bar?
(4) The diameter of the wheel of the bicycle is 0.65 meters long. If it turns 100 circles per minute, how many minutes will it take for the bicycle to cross the 6700 meter bridge? (keep the number in integer)
Be optimistic about problems and problems in calculation (to round the formula and formula and process, not only the answer)
This is the circumference of a circle

1) 2 π r = 2 × 3.14 × 6378 = 40054 (km) 2) 2 π R × 100 = 2 × 3.14 × 1.5 × 100 = 942 (CM) 3) list the equation 2 π R × 10 = 628, find out R = 10 mm, s = π R × R (I can't square, I hope you can understand) = 3.14 × 10 × 10 = 314 (square mm) 4) perimeter is: π d = 3.1

(1) The diameter of the driving wheel of the locomotive is 1.5 meters. If it turns 350 cycles per minute, how many meters does the locomotive advance per minute? (2) a circular Street Garden, mischievous measurement shows that its perimeter is 31.4 meters, and how many meters is the diameter of the street garden? There is a 2-meter-wide path around the garden, and how many square meters is the area of the path?
(3) There is a rectangle. Its length and width are increased by 8cm respectively. The area of this rectangle is increased by 208 square centimeters. What is the circumference of the original rectangle?

1. The circumference of wheel C = 3.1416 × 1.5/2
Train speed = 350 × C (M / min)
2. Let the original rectangle be long a and wide B
Then (a + 8) × (B + 8) - AB = 208
64+8（a+b）=208
a+b=144/8=18
So perimeter = 2 × (a + b) = 36

Put two fifths, one third and three eighths in a certain order

Two fifths more than three eighths more than one third

If the square of X - 3xy = 6 and the square of 3xy + y = 10, then the square of X + the square of Y=
most urgent!
It's 3xy + y squared = 10

X²-3xy=6
3xy+Y²=10
Add to get X & # 178; + Y & # 178; = 16

1+1/2+1/3+2/3+1/4+2/4+3/4+...+1/100+2/100+...+99/100.

1+1/2+1/3+2/3+1/4+2/4+3/4+...+1/100+2/100+...+99/100 ＝1+1/2+(1/3+2/3)+(1/4+2/4+3/4)+(1/5+2/5+3/5+4/5)+…… +（1/100+2/100+...+99/100） ＝1+（0.5+1+1.5+2+2.5+…… +49.5） ＝1＋（0.5＋49.5）×99/2 ＝1＋2...

Given that a and B are rational numbers and a is not equal to B, then the square of a plus the square of B () a must be non negative, B must be non positive and C must be negative
D must be positive

D

A sufficient and necessary condition for solving the equation of X: the square of AX + 3x-2 = 0 (a ≠ 0) to have at least one positive root

If there is at least one positive root, then first, △ > = 0, that is 9 + 8A > = 0, then a > = - 9 / 8
Then, if x = - 3 / 2A > 0, AA > = - 9 / 8
I don't understand
hey

Five 15 is______ ，______ 18 is one, 6 is 17______ It's in 512______ 112

According to the meaning of the fractional unit, five 15s are 55 = 1, 1 = 88, so eight 18S are 1, six 17s are 67512, in which there are five 112