The length of the railway between a and B is 385 km. The two trains run from two stations at the same time. After two minutes and three hours of meeting, the two trains are known The speed of the train is 6:5. How many kilometers do two trains travel per hour?

The length of the railway between a and B is 385 km. The two trains run from two stations at the same time. After two minutes and three hours of meeting, the two trains are known The speed of the train is 6:5. How many kilometers do two trains travel per hour?

Speed sum = 385 △ 3 / 2 = 770 / 3km / h
Speed of car a = 770 / 3 △ 6 + 5 × 6 = 140 km / h
Vehicle B speed = 770 / 3-140 = 350 / 3km / h

Two mathematical problems of basic inequality in senior one
1. If a > 0 and b > 0 are known, then the minimum value of AB under 1 / A + 1 / B + 2 * radical is?
2. If the image of function y = a ^ 1-x (a > 0, a is not equal to 1) passes through the fixed point a, if the point a is on the straight line MX + NY-1 = 0 (M > 0, n > 0), then the minimum value of 1 / M + 1 / N is?

(1) 1 / A + 1 / B + 2 √ AB = (a + b) / AB + 2 √ ab ≥ 2 / √ AB + 2 √ ab ≥ 4, (a = b = 1, equal sign)
The minimum is 4
(2) When y = a ^ 1-x (a > 0, a is not equal to 1), the image passes through the fixed point a (1,1), and a is on the straight line MX + NY-1 = 0 (M > 0, n > 0)
∴m+n=1
∵ 1 / M + 1 / N = (M + n) (1 / M + 1 / N) = n / M + m / N + 2 ≥ 4 (M = n = 1 / 2, equal sign)
The minimum value of 1 / M + 1 / N is 4

The distance between a and B is 460 km. A truck and a bus leave each other at the same time. Two cars meet 2.5 hours later [grade five questions]
The distance between a and B is 460 km. A freight car and a passenger car leave from the two places at the same time. After 2.5 hours, the two cars meet. It is known that the speed of freight car is 1.3 times that of passenger car. How many kilometers do freight car and passenger car walk each hour

Arithmetic method
Bus speed: 460 △ 2.5 △ 1 + 1.3 = 80 (km / h)
Truck speed: 80 × 1.3 = 104 (km / h)
Equation method
The bus is set to travel x kilometers per hour
2.5(x+1.3x)=460
2.3x=184
x=80
80 × 1.3 = 104 (km / h)
A: freight cars travel 104 kilometers per hour and passenger cars 80 kilometers per hour

A = 3, B = - 5, C = - 7, find the value of a-b-c

a-b-c
=3-(-5)-(-7）
=3+5+7
=15

There are 327 people in a city's fire brigade a and B. a quarter of the number of fire brigade a and a third of the number of fire brigade B are transferred, and a total of 98 people are transferred

There are 132 persons in fire brigade a and 195 persons in fire brigade B

If may day is a Wednesday, what day is the National Day?

There are 153 days from May day to national day (counting the end but not the head). 153 △ 7 = 21 ······· 6, counting six days from Wednesday. The national day of this year is Tuesday

The "100 km acceleration time" of a small car is the minimum time from stationary to 100 km / h, and the acceleration time is 11.3 s

100km/h=27.78m/s
Acceleration a = (vt-v0) / T = (27.78-0) / 11.3 = 2.46m/s ^ 2

If a = 5 / 3, B = 4, then C = 90 ° in RT △ ABC=
Such as the title

C = radical (A & sup2; + B & sup2;) = 13 / 3

A and B start from ab at the same time and travel in opposite directions. Car a travels 40 kilometers per hour and car B travels 48 kilometers per hour. When car B reaches two fifths of the whole journey, car a is 30 kilometers away from the midpoint, so we can find the distance between a and B

A / b speed ratio = 40:48 = 5:6
Therefore, when vehicle B reaches two fifths of the whole journey, 2 / 5 △ 6 × 5 = 1 / 3 of the whole journey
So the distance between a and B is 30 (1 / 2-1 / 3) = 180 km

If the constant terms of the polynomials X & # 178; - 8x-1 and 3x & # 178; + 4x-n are the same, the value of n-1 / N is obtained

If the constant terms are the same, then - 1 = - N, n = 1
n-1/n=1-1=0