Put the three numbers 1, 5 and 6 into three digit prime numbers

Put the three numbers 1, 5 and 6 into three digit prime numbers

It is impossible to have an answer, because 1 + 5 + 6 = 12, 12 is a multiple of 3, so no matter what kind of three digits 1, 5 and 6 are used, they can be divided by 3, so there is no solution to this problem

The sum of three different prime numbers is 82. What is the maximum product of these three numbers?

All prime numbers except 2 are odd. If there is no 2 in the three prime numbers, then there must be three odd numbers, and the sum of them must be odd

The unit price of 100 watt incandescent lamp and 40 Watt energy-saving lamp is 2 yuan and 23 yuan, and the electricity price of xiaowangjia is 0.5 yuan. How long is the service life of the two lamps? It's cost-effective to choose energy-saving lamp

The power consumption of incandescent lamp per hour: 0.100 kW * 1 hour * 0.5 yuan = 0.05 yuan, the power consumption of energy-saving lamp: 0.040 kW * 1 hour * 0.5 yuan = 0.02 yuan
If the two residual values are the same when x is a child, then:
0.05*x+2=0.02*x+23
The solution: x = 21 / 0.03 = 700 hours

Factorization: 3A ^ 2 - 7ab - 6B ^ 2

Electric power law in series parallel circuit

Series circuit:
R1:R2＝U1:U2＝P1:P2
Ptotal = P1 + P2, P is the actual power;
Parallel circuit:
R1:R2＝I2:I1＝P2:P1
Ptotal = P1 + P2
P = UI = u ^ 2 / r = I ^ 2R, which is common to pure resistance circuit

First simplify, then evaluate (3m-5m + 4Mn) - (2m-4n + 6mm)
Attention is 6mm! When M-N = 7, Mn = - 5

(3M-5N+4MN)-(2M-4N+6MM)
=M-N-2MN
=7+2X5
=17

Electric power
An air conditioner is connected to the watt hour meter marked with "1500revs / (kW · h)", and the rotary table of the watt hour meter is rotated by 500 turns after the air conditioner is cooled continuously for 10 minutes. How much power is consumed by the air conditioner during this period? If the work done by the current is 0.3kw · h, how many turns is the rotary table of the watt hour meter?

E=w=500/1500=1/3kw.h=1.2*10^6J
If the power consumption is 0.3kw. H:
0.3:1=n:1500
N = 450 rpm

The stiffness coefficient of a light spring is 100N / m, and the original length of the spring is 10cm. The upper end of the spring is fixed, and the other end is hung with a 1n weight weight
The stiffness coefficient of a light spring is 100N / m, and the original length of the spring is 10cm. Connect three such springs one by one, and hang a 1n weight at the end of the lowest spring. What is the total length of the three springs?

The total length of each piece is 33cm because the force is 1n and the elongation is 1 / 100 = 1cm

Write the relationship between current and voltage of resistance, inductance and capacitance

ur=ir*R
uL=LdiL/dt
ic=Cduc/dt
All of them are instantaneous values, no matter AC, DC or dynamic voltage and current

A car m is on a smooth horizontal plane. Then a slider m slides on the car and stops for a period of time. The friction force is F. what is the acceleration of the car?
If the acceleration of the slider is f / m, is the acceleration of the car f / m or F / (M + m)

Separately study the slider: F = ma, the acceleration of the slider is a = f / m,
Study the car separately: F = ma ', the acceleration of the car is a' = f / m