Xiaohong and Xiaoqiang start from home at the same time. Xiaohong walks 52 meters per minute and Xiaoqiang 70 meters per minute. They meet at a on the way. If Xiaohong starts 4 minutes ahead of schedule and Xiaoqiang walks 90 meters per minute, they still meet at a. how many meters are Xiaohong and Xiaoqiang's homes apart?

Originally, the speed ratio of Xiaohong and Xiaoqiang was 52:70 = 26:35, then Xiaoqiang walked the whole course when they met: 35 ÷ (26 + 35) = 3561; later, the speed ratio of Xiaohong and Xiaoqiang was 52:90 = 26:45, when they met, Xiaoqiang also walked the whole course of 3561, then Xiaohong walked the whole course after Xiaoqiang started 3561 × 2645 × = 182549; the distance between Xiaohong's and Xiaoqiang's houses: (52 × 4) / (1-3561-182549) = 208 × 54952, = 2196 (m). A: the distance between Xiaohong's and Xiaoqiang's houses is 2196 M

Xiaoming, Xiaoliang, Xiaogang and Xiaoying's house are just on a straight street. If Xiaoming's house is 600 meters away from Xiaoying's house, the distance from Xiaogang's house to Xiaoming's house is from Xiaoying's house
Xiaoming, Xiaogang, Xiaoliang and Xiaoying's house are just on a straight street. If Xiaoming's house is 600 meters away from Xiaoying's house, the distance from Xiaogang's house to Xiaoming's house is 1 / 2 times that to Xiaoying's house. Xiaoliang's house is in the middle of Xiaoming's house and Xiaoying's house. Please calculate the distance between Xiaogang and Xiaoying's house?
Amount. Sales false = xiaoliangjia

900 meters or 100 meters;
In the first case, if Xiaogang's house is outside the connection between Xiaoming's house and Xiaoying's house and X meters away from Xiaogang's house, then x = 1 / 2 * (x + 600); the solution is x = 600;
In the second case, if Xiaogang's house is in the line between Xiaoming's house and Xiaoying's house and X meters away from Xiaogang's house, then x = 1 / 2 * (600-x); the solution is x = 200

Electric lamps L1 and L2 are marked with 220V 60W and 220V 100W respectively. If they are connected in series in the lighting circuit, what is the voltage ratio of the two lamps? Which lamp is brighter?

5: 3 L1 brighter

Calculation: (- 23) - (- 134) - (- 123) - (+ 1.75)

（-23）-（-134）-（-123）-（+1.75）=-23+123+134-1.75=1．

The coil resistance of a DC motor is 2 Ω. When it works, the current passing through the coil is 5A and the voltage applied at both ends is 220 v. then the electric work done and the heat generated in 5 minutes are ()
A. 3.3×105J，1.5×104JB. 1.5×104J，3.3×105JC. 3.3×105J，3.3×105JD. 1.5×104J，1.5×104J

1min = 60s, the electric work of the motor in normal operation: w = uit = 220V × 5A × 5 × 60s = 3.3 × 105J; the heat generated by the motor in t = 5min: q = i2rt = (5a) 2 × 2 Ω × 5 × 60s = 1.5 × 104j; so a

Can 6.4 plus 0.74 plus 3.7 plus 0.26 be simplified?

6.4+0.74+3.7+0.26
=(6.4+3.7)+(0.74+0.26)
=(6.4+3.6+0.1)+1
=(10+0.1)+1
=11.1
We use the law of additive commutation

The energy released from the fission of 1kg uranium is more than that from the complete combustion of 2000t coal. Please calculate the joule of this energy

3.36 × 10 ^ 7 * 2000 * 10 ^ 3 = 6.72 × 10 ^ 13 joules

How to solve the fractional equation 6 / 60-x = 10 / 80-x, X / X-5 = X-2 / X-6

The first step is to multiply both sides of the equation by the least common multiple of the left and right fractions, that is, to remove the denominator
The second part is to solve the equation
The third step is to find X
The fourth part is to see whether the denominator is 0, excluding the root
Method is more important. Mastering method is better than doing 100 questions

Wind energy is a kind of environmental protection energy. Wind power generation is to convert the kinetic energy of the wind into electric energy. Let the air density be ρ, the horizontal wind speed be V, the length of each blade of the wind turbine be l, and the efficiency of converting all wind energy into electric energy in the circle surrounded by the rotation of the blades be η, then the mathematical expression of the generating power P of the wind turbine is ()
A. 12ηρπLvB. 12ηρπL2v2C. 12ηρπL2v3D. 12ηρπL2v4

The mass of air flowing through the generator in time t is: M = ρ (π L 2 · VT) & nbsp; & nbsp; ① the efficiency of converting wind energy into electric energy is η. According to the law of conservation of energy, there are: 12mv 2 · η = Pt & nbsp; & nbsp; ② simultaneous solution: P = 12 η ρ π l 2V 3, so C

(1) If 3x + 2Y = - 2, find the value of t power of 9 and 3x power of * 3
(2) Solving binary linear equations
m-n+2n+1=11
｛m-1+4-n=5
Finding the value of M, n

(1) 9 to the power of Y * 3 to the power of 3x
=2Y power of 3 * 3x power of 3
=3x + 2Y power of 3
=The - 2 power of 3
=1/9
(2)m-n+2n+1=11
｛m-1+4-n=5
m+n=10
｛m-n=2
m=6
{n=4