a. B is two arbitrary rational numbers. Compare the size of a + B and B

a. B is two arbitrary rational numbers. Compare the size of a + B and B

If a ≥ 0, then a + B ≥ B; if a ≤ 0, then a + B ≤ B

If the sum of two rational numbers is a and the difference between the two numbers is B, then the size relationship between a and B is ()
A. A ＞ BB. A ＜ BC. A = BD

If the sum of two rational numbers is a and the difference between the two numbers is B, then the size relationship between a and B cannot be determined

Electric flower basket heater model: NSB ~ a rated power: 1000W rated voltage: 220V rated frequency: 50Hz how many kilowatts of electricity do you use per hour
Electric flower basket heater
Model: NSB ~ A
Rated power: 1000W
Rated voltage: 220 V
Rated frequency: 50 Hz
How many kilowatts of electricity do you use in an hour

Rated power: 1000W
That is, the normal work is one hour electricity

(m ^ 2 + 4N ^ 2): Mn = 4:1 find the value of M: n

(m^2+4n^2):mn=4:1
m^2+4n^2=4mn
m^2-4mn+4n^2=0
(m-2n)^2=0
m=2n
m:n=2

Two lamps marked with 220 V and 100 W are connected in series to 200 V, and the total power consumed by these two lamps is

R=U*U/P=48400/100W=484Ω
The total resistance of two series connection is 968 Ω
When connected to 200V circuit, the total power is p = u * U / r = 40000 / 968 Ω = 41.32w
Both bulbs are dark at this time

The random variable (x, y) obeys uniform distribution in the region g = {(x, y) | 0 ≤ x ≤ 2,0 ≤ y ≤ 1}, and the probability density FZ (z) of Z = XY is obtained
2. Let a and B be two random variables, P (a) = 0.4, P (b) = 0.5, P (a | b) = P (a | B not), then p (AB not)=

If the area of the domain is 2x1, the total density is 1 and the distribution is uniform, the density function is always 1 / 2
Fz(z)=P(Z=z)=1-∫(1/2~1)(1/y~2) f(x,y)dxdy
f=F'
P (a | b) = P (a | B non)
So the probability of occurrence of a has nothing to do with B
P (AB non) = P (a) P (b non) = 0.4 * (1-0.5) = 0.2

Why is the current of one consumer in series much higher than that of other consumers? This consumer is at the negative pole of the power supply

Theoretically, in series circuit, the current is equal everywhere, there is no problem you said
In practical application, because some electric appliances may leak to the ground, the current of electric appliances connected in series at the ground terminal will be relatively small

The boiling points of various components in the air are different. For example, the boiling point of nitrogen is - 196 ℃ and that of oxygen is - 183 ℃. If air is used as raw material in industry to produce a large amount of oxygen, what method can be adopted?

In industry, oxygen is separated according to the different boiling points of oxygen and nitrogen. Firstly, the air is cleaned to remove carbon dioxide and water vapor, and then pressurized at low temperature to liquefy the air

The power of an energy-saving lamp is 10 watts (0.01 kW), and the price is 60 yuan; the power of an incandescent lamp is 60 watts (0.06 kW),
The price is 3 yuan. The lighting effect is the same and the service life is the same. If the electricity price is 0.5 yuan / (KWH)
How long does it take for the two lights to cost the same
2. Suppose two kinds of lights have 3000 hours. If you plan to light for 3500 hours, plan the most cost-effective plan (to be compared)
By 12 o'clock tomorrow
Let's say the two lights only last 3000 hours

1. Let two kinds of lamps use the same time for X hours
0.01 × 0.5x + 60 = 0.06 × 0.5x + 3: x = 2240 hours
2. If the energy-saving lamp is used, the cost of 3500 hours is 3500 × 0.5 × 0.01 + 60 × 2 = 137.5 yuan
If incandescent lamp is used, the cost of 3500 hours is 3500 × 0.5 × 0.06 + 3 × 2 = 111 yuan
After comparison, we know that for 3500 hours of lighting, incandescent lamps are the most economical

(1) Given that the sum of the first n terms of the sequence is Sn = n & # 178; + 2n + 1, find the value of A7 + A8 + A9
(2) There are four numbers, of which the first three numbers are equal difference series, and the last three numbers are equal ratio series. The sum of the first number and the fourth number is 14, and the sum of the second number and the third number is 12,

1. Sn = n & # 178; + 2n + 1 = (n + 1) & # 178; A7 + A8 + A9 = s9-s6 = (9 + 1) & # 178; - (6 + 1) & # 178; = 10 & # 178; - 7 & # 178; = 100-49 = 512