On a 1:6000000 map, the distance between Beijing and Shanghai is 17.5cm How many hours does it take for a car to go from Beijing to Shanghai at the speed of 84 kilometers per hour?

On a 1:6000000 map, the distance between Beijing and Shanghai is 17.5cm How many hours does it take for a car to go from Beijing to Shanghai at the speed of 84 kilometers per hour?

According to the scale, the actual distance between Beijing and Shanghai is 6000000 * 17.5 = 105000000cm = 1050km
Vehicle speed v = 84 km / h, so
Time t = s / v = 1050 / 84 = 12.5 hours

On the parabola y ^ 2 = 2x, the minimum distance from a point P to the straight line X-Y + 3 = 0 is? (two methods are needed,

Let P point coordinate P (Y0 & sup2 / / 2, Y0). The first method is formula method. When the distance d = | Y0 & sup2 / / 2-y0 + 3 | / √ (1 & sup2; + (- 1) & sup2;) = | (1 / 2) (y0-1) & sup2; + 3 / 2 | / √ 2y0 = 1, there is the minimum distance d = 3 / 2 √ 2 = 3 √ 2 / 4. The second method is to make a known straight line vertical line through P, find the vertical foot coordinate, and then find P and

12 of a is equal to 13 of B, and neither of them is zero
A. Greater than B. less than C. equal to

Because: 1 × 12 ／ 13 = 12 ／ 13 = 112112 ＞ 1, so: a number < B number, so choose: B

An enterprise produces two kinds of products a and B. It is known that 3 tons of raw material a and 2 tons of raw material B are needed to produce each ton of product a; 1 ton of raw material a and 3 tons of raw material B are needed to produce each ton of product B. the profit can be 50000 yuan per ton of product a and 30000 yuan per ton of product B. the enterprise consumes no more than 13 tons of raw material a and no more than 18 tons of raw material B in a production cycle. How to arrange the production of the enterprise What is the maximum profit for the industry? What is the maximum profit?

Suppose that the enterprise produces x tons of a product and Y tons of B product, then the enterprise can obtain the profit z = 5x + 3Y, and X ≥ 0y ≥ 03x + y ≤ 132x + 3Y ≤ 18, and the simultaneous 3x + y = 132x + 3Y = 18. The solution is x = 3Y = 4. From the figure, the optimal solution is p (3,4), and the maximum value of Z is Z = 5 × 3 + 3 × 4 = 270000 yuan

Two cars of a and B travel from two places 420 meters apart at the same time. After meeting for 3 hours, it is known that car a travels 10 kilometers more per hour than car B. the speed of car a and B is calculated

The sum of speed of a and B = 420 / 3 = 140
Speed of a = (140-10) / 2 = 130 / 2 = 65 km / h
Speed of B = 65-10 = 55 km / h

[mathematics] a problem about "inequality system"
When a is a value, the solution of the system ax-4y = 8,3x + 2Y = 6 is positive
Please write a detailed process, thank you!

From 3x + 2Y = 6
We get y = 3-1.5x
If Y > 0, then 1.5x

The distance between a and B is 360 km. The passenger cars and freight cars run from each other and meet two hours later. It is known that the passenger cars run 98 km per hour and the freight cars run 98 km per hour
How many kilometers do you travel? How many kilometers do buses travel more than trucks when they meet?

Hello
Truck per hour:
360÷2-98
=180-98
=82 (km)
When meeting, passenger cars drive more than freight cars
（98-82）×2
=16×2
=32 (km)

In the cube abcd-a1b1c1d1 with edge length of 1, e and F are the points on the side diagonal BC1 and AD1 respectively, if the area of the quadrilateral bed1f projected on the bottom ABCD is

If you project points E and F to the bottom respectively, you will know the quadrilateral of the projection. The area is equal to 0.5 * 1 = 0.5

The original number ratio of team a and team B is 7:3. After some people are transferred from team a to team 1, the number ratio of team a and team B is 3:2. Team B has 120 people. How many people is team B

A current number = 120 * (3 / 2) = 180
Total = 180 + 120 = 300
B = 300 * (3 / 10) = 90

What is the number of N consecutive natural numbers starting from 1?

The number of N consecutive natural numbers starting from 1 is n