Xiaoming is doing experiments at home. His electricity meter is marked with 3000r / kWh. Xiaoming only lets one electric appliance work and observes that the turntable turns 75r in two minutes What's the working voltage of the appliance? What's the current? What's the resistance? Write down the calculation process. 20 points for you

220 V (home circuit)
3000r: 1kW. H = 75r: w (total work)
W=90000J
t=120s
P=W/t=750W
P = UI, I = P / u = 3.4A
R = u / I = 65 Ω

Factorization of (a + b) (B + C) (c + b) + ABC

(a+b)(b+c)(c+b)+abc
=a²b+a²c+ab²+2abc+ac²+b²c+bc²+abc
=(ab+bc+ac)(a+b+c)

It is known that the mass of a carbon atom is 1.993 * 10 to the - 26th power kg, and the mass of M atom is 6.64 * 10 to the - 26th power kg?
A 0.161 * 10 to the - 26th power
b 40
The - 26th power of C 6.64 * 10
thirty-three point nine

The relative atomic weight is the ratio of 1 / 12 mass of C
So C is 12, let m be X
According to the proportion
12: The - 26th power of x = 1.993 * 10: the - 26th power of 6.64 * 10 = 3:10
That is 3x = 120
The solution is x = 40
Take it out. It's ca

Use - 3, - 5,0, + 3, + 4 to make the result 24 and write the formula

[(-3)-(-5)]*(+3)*(+4)+0=24

Power supply voltage 3V, close switch s, ammeter A1 indication 1.2A, ammeter A2 indication 0.3A

A2 is connected with R2, A1 is on the main road
1、I1=I1-I2=1.2-0.3=0.9A
2. R2 = 3 / 0.3 = 10 Ω

The continuous natural numbers with two prime numbers are () and ()

The continuous natural numbers with two prime numbers are (2) and (3)

Connect the 10 ohm and 20 ohm resistors in series and connect them to the power supply. If the voltage at both ends of the 10 ohm resistor is 5V, what is the voltage at both ends of the other resistor and the power supply voltage?

x²-32x+100=0 ）

x²-32x+100=0
(x-16)²-256+100=0
(x-16)²=156
X-16 = ± root 156 = ± 2 root 39
X = 16 ± 2 root sign 39

What are the factors related to the resistance

It is directly proportional to the resistivity and length of the material, and inversely proportional to the cross-sectional area

Two solutions to equations and one practical problem
(X-7 / 11) * 7 / 11 = 7 / 11 x: 3 / 8 = 8:8
Practical questions:
There are some digital cards which are written in multiples of 3 or 4. Among them, there are 20 cards with multiples of 3, 4 and 12. How many of these cards are there?
There's no need to calculate the practical problem, I've worked it out

(x - 7 / 11) × 7 / 11 = 7 / 11x - 7 / 11 = 7 / 11 ﹣ 7 / 11x = 1 + 7 / 11x = 18 / 11x: 3 / 8 = 8: 3 / 53 / 5x = 8 × 3 / 8x = 3 ﹣ 3 / 5x = 512 multiple of card → both 3 and 4 multiple. 2 / 3 + 3 / 4 = 17 / 1217 / 12 - 1 = 5 / 1220 ﹣ 5 / 12 = 48