It's not that the ratio of density is equal to the ratio of molar mass In this case, the density of methane should be 16:18 than that of water But the relative density (water = 1) is 0.42

It's not that the ratio of density is equal to the ratio of molar mass In this case, the density of methane should be 16:18 than that of water But the relative density (water = 1) is 0.42

They are all gases. At the same temperature and pressure, the density ratio is the molecular weight ratio
Water is a liquid and methane is a gas. This rule cannot be used

Calculation formula of VAT
Known conditions, tax rate 17%, including tax price: 2480, please ask the calculation formula of tax and unit price

First, the price including tax is changed into the price excluding tax = price including tax / (1 + 17%) = 2480 / (1 + 17%) = 2119.66
Then the amount of tax payable = price excluding tax * 17% = 2119 * 17% = 360.3422

When a 3V voltage is applied at both ends of a resistor, the current passing through it is 0.2A
When a 3V voltage is applied at both ends of a resistor, the current passing through it is 0.2A. If the current passing through it is increased by 0.1A, the voltage should be applied at both ends of the resistor?

When 3V is added at both ends of the resistance, the current is 0.2A. According to Ohm's law, the resistance is 3V / 0.2A = 15 ohm. If 0.1A is added, it means that 0.3A is added in the original resistance circuit, and the voltage at both ends of the resistance should be 0.3x15 = 4.5V

The last three digits of the square of a natural number are 876. What is the minimum number?

To ask for the smallest natural number is to find the smallest integer whose last three digits are 876, and the integer is a square number. The last digit is 6. If you want to multiply two identical numbers to get 6, the last digit is 4 or 6. If it is 4, you need to enter 1 when calculating the addition, that is, the square of the number in the penultimate digit or the penultimate digit of 6

The resistance of the bulb is 10 ohm, and the normal working voltage is 6V. If the small bulb is connected to 9V power supply
How large a resistor should be connected in series in order to make it work normally?

Series resistance should be divided into: U2 = u-u1 = 9-6 = 3 (V)
Current of bulb in normal operation: I1 = U1 / R1 = 6 / 10 = 0.6 (a)
The current of series circuit is equal everywhere, so I2 = I1 = 0.6 (a)
Resistance value of series connection: R2 = U2 / I2 = 3 / 0.6 = 5 (Ω)
A: slightly
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Solving the equation A & # 178; (X & # 178; - x + 1) - A (X & # 178; - 1) = (A & # 178; - 1) x with respect to X

a²（x²-x+1）-a（x²-1）=(a²-1)x
a²x²-a²x+a²-ax²+a=a²x-x;
(a²-a)x²+(1-2a²)x+a²+a=0;
[ax-(a+1)][(a-1)x-a]=0;
Ax - (a + 1) = 0 or (A-1) x-a = 0;
X = (a + 1) / A or x = A / (A-1);
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On the factors affecting conductor resistance
In the activity of exploring the factors that affect the resistance of conductor, Xiao Ming found that there is only one wire in the experimental equipment, and other equipment is enough. If he wants to complete some of the following exploration activities, what he may complete is
① To explore the relationship between conductor resistance and length; to explore the relationship between conductor resistance and cross-sectional area
③ To explore the relationship between conductor resistance and material (4) to explore the relationship between conductor resistance and temperature
Why is it right? Why is it wrong

② After the wire is folded in half, cut it, use one wire to measure the resistance, and connect two wires in parallel, the resistance is half of one wire
④ There is no heater
Thank you for your question

How to solve equations quickly in practical problems

My master's master said that the equation is generally slow, so you can know the result by mental calculation

How many kilowatts of electricity will be consumed by an 800 w electric appliance working for half an hour

One kilowatt hour is the electricity consumption of 1000 W electrical appliances in one hour, and so on. 0.8 * 0.5 = 0.4 is 0.4 kilowatt hour

Using factorization to calculate 100992 + 198 + 1=______ ．

100992 + 198 + 1 = 100 (99 + 1) 2 = 1100 or 0.01