Ask the people's education press for the answers to questions 1-4 on page 29 of physics, Volume 2, Grade 8

1.I=U\R=220V\97Ω=2.27A
2.0.1kΩ=100Ω U=IR=2.1A×100Ω=210V
3.250mA=0.25A R=U\I=2.2V\0.25A=8.8Ω
4.R=R1+R2=5Ω+15Ω=20Ω I=U\R=6V\20Ω=0.3A

The key knowledge about the change of state of matter in the eighth grade physics Volume 1

There are three basic physical states of matter: solid state, liquid state and gas state. The process of matter changing from one state to another is called change of state of matter. The process of change of state of matter includes: Melting: solid → liquid (endothermic) iron turns into molten iron; solidification: liquid → solid (exothermic) water turns into ice; molten steel casts into wheel; vaporization: liquid

1. Put the ice with a temperature of - 5 into the water at 0 ℃ for a period of time, will the mass of ice increase or decrease? Why?
two

Correct answer: the mass of ice will increase
Reason: - 5 ice needs to absorb heat from 0 ℃ water, but the temperature of water is only 0 ℃, the temperature of ice can only rise to 0 ℃ at most, so it can no longer absorb heat, so it will not melt. But after the water releases heat, part of the water will solidify, so the mass of ice becomes larger

How to calculate the building elevation
It is known that the reading of the tower ruler at - 1.2m elevation is 0.695m. Now I want to calculate the reading of the elevation at - 5.8m and find the calculation formula
Is it - 1.2 + 0.695 - (- 5.8)

Tell you a general formula, known elevation + degree of the post - the second elevation = degree of the second elevation
Known elevation + degree of post - degree of second elevation = second elevation
So you're right

The difference and relationship between unbounded variable and unbounded quantity in Higher Mathematics
How to know that (1 / x) * [cos (1 / x)] is an unbounded variable when x tends to zero?

Because the range of COS (x) is always always in [- 1,1], so cos (1 / x)] is a bounded quantity, and 1 / X is an unbounded quantity when x tends to 0. Therefore, according to the theorem, a bounded quantity multiplied by an unbounded quantity equals an unbounded quantity, and exit (1 / x) * [cos (1 / x)] is an unbounded variable

63-x = 45, quick, I'll hand it in tomorrow!

63—x=45
x=63-45
x=18

In the first quarter of a farm tool factory, the consumption of electricity was m yuan, and the consumption of water was 40 yuan less than 2 times of the electricity. In the second quarter, the electricity cost was saved by 20%, and the water cost was 5% more. How many yuan were saved in the second quarter compared with the first quarter

According to the meaning of the question: (M + 2m-40) - [80% m + (2m-40) × (1 + 5%)] = 0.1M + 2 yuan. A: the water and electricity charges of the plant in the second quarter were 0.1M + 2 yuan less than those in the first quarter

Finding the integer solution of the system of inequalities x-3 / 2 (2x-1) ≤ 4,1 + 3x / 2 〉 2x-1

{x-3 / 2 (2x-1) is less than or equal to 4
2X-6X+3=-5/4
1 + 3x / 2 greater than or equal to 2x-1
2+3X>=4X-1
X

1+2+3+4+5+6+5+4+3+2+1666666×666666．

1+2+3+4+5+6+5+4+3+2+1666666×666666，=(1+5)+(2+4)+(3+3)+6+(5+1)+(4+2)666666×666666，=6×6666666×666666，=1111111×111111，=112345654321．

12341234124 * 2345-1234 * 2345234345 answers

123412341234*2345-1234*234523452345
=1234*100010001*2345-1234*2345*100010001
=0

Ask the people's education press for the answers to questions 1-4 on page 29 of physics, Volume 2, Grade 8