Seven monkeys ate peaches and 13 peaches in total. In order to know how many big monkeys there are, each big monkey ate three peaches and each little monkey ate two peaches?

Seven monkeys ate peaches and 13 peaches in total. In order to know how many big monkeys there are, each big monkey ate three peaches and each little monkey ate two peaches?

wait a moment

Big monkey eat three peaches, little monkey two eat one peach, 25 monkeys, 60 peaches, a few big monkeys, a few little monkeys

25x3 = 75
75-60 = 15
Monkey: 15 ÷ (3-1 / 2) = 6
Monkey: 25-6 = 19

There are seven monkeys eating 13 peaches, three for each big monkey and one for each little monkey. How many big monkeys are there?

There were x large monkeys and (7-x) small ones
From the meaning of the title, we know that 3x + (7-x) = 13
The solution is x = 3
A: there are three big monkeys
Where don't understand the words, understand the words to a adoption oh

Three phase current calculation formula
How many square wires do you need for 210Kw capacity? The power supply is 380V
xv

Calculation formula of three-phase resistance electric power = 1.732 * line voltage U * line current I (star connection)
=3 * phase voltage U * phase current I (angle connection method)
Calculation formula of three-phase motor electric power = 1.732 * line voltage U * line current I * power factor cos Φ (star)
(connection)
=3 * phase voltage U * phase current I * power factor cos Φ (angle connection method)
In three-phase AC circuit, the two power calculation formulas of star connection and corner connection can be used interchangeably, but the phase voltage, line voltage, phase current and line current must be distinguished
The capacity of 210Kw, the power supply is 380V, the current can reach more than 400A, so the power line should be more than 100mm2

Reduction - 4x ^ 2yz ^ 3 / 16xyz ^ 5 2 (X-Y) ^ 3 / Y-X general score: 2 / 9-3a and A-1 / A ^ 2-1, given x + 1 / x = 3, find the value of x ^ 2 / x ^ 4 + x ^ 2 + 1

First, I don't understand. Is the whole fraction?
Question 2, (2-27a) / 9; (a ^ 2 + A-1) / A ^ 2
Question 3, 8

A "220V 25W" bulb is connected to the power supply of u = 220 sin (314T + 60 °) v. try to find: 1) the working resistance of the bulb; 2) the expression of the instantaneous value of the current; 3) the working resistance of the bulb;

The working resistance of the bulb is its own resistance, and its value remains unchanged: r = u ^ 2 / P = 220x220 △ 25 = 1936 (Ω)
The instantaneous value of current is the ratio of instantaneous value of voltage to resistance value, I = u / r = 220sin (314T + 60 °) / 1936 = (5 / 44) sin (314T + 60 °) a

If the polynomial KX ^ 2-9xy-10x ^ 2 is decomposable factor (MX + 2Y) (3x-5y), then k =? Then M =?

The question should be 10Y ^ 2, not 10x ^ 2
kx^2-9xy-10x^2=（mx+2y)(3x-5y),
kx^2-9xy-10x^2=3mx^2-5mxy+6xy-10y^2
kx^2-9xy-10x^2=3mx^2-10y^2+xy(6-5m)
k=3m
-9=6-5m
m=3
k=9

A certain watt hour meter is marked with "3000revs / kW. H". If the watt hour meter turns 30 turns while watching a certain TV program,
If we know that the power of the TV is 50W, then watching this TV program consumes a total of --- - J's electric energy and --- - min

1.3.6 times 10 to the fourth Joule
2.12 minutes

Solve the equation with proper method
x²＋2ax－3a²=0
x²－2mx＋m²=n(n＞0)
(3x-1)(x+3)=1
(y+1)²-2(y-1)²=6y-5
(formula method and factorization method can be used...)
Fill in the blanks
When the left side of equation 1 / 3-x-4 = 0 is combined into a complete square formula, the resulting equation is ()

1. (x + 3a) (x-a) = 0, then x = a or x = - 3a
2, (x-m) & sup2; = n  x = m + sqrt (n) or x = m-sqrt (n)
3. The equation 3x & sup2; + 8x-4 = 0 is obtained, and x = (- 4 ± 2sqrt (7)) / 3 is obtained by formula method
4. After splitting and combining the similar terms, we get - Y & sup2; + 4 = 0, y = ± 2
I can't understand the question

After learning the knowledge of electric power, Xiao Ming used the energy meter and watch at home to measure the data of some household appliances
When a refrigerator is working normally, he measures the electric energy meter to rotate three times a minute to calculate the electric energy consumed by the refrigerator during this period
1500 R / kWh means 1 kwh for 1500 turns
1kwh=3600000J
Then 3 turns means 3 / 1500 = 1 / 500 (KWH) = 3600000 * 1 / 500 = 7200 (J)
Why doesn't one minute turn into an hour? Is kilowatt hour corresponding to an hour?

1kwh (kilowatt hour) = 1000W electrical appliances work for 1 hour, the work done by electrical energy = 1000W * 3600 seconds = 3600000 joules. It is the auxiliary unit of work. 1500r / kWh means that the watt hour meter turns 1500 circles and the electrical appliances do 1kwh, then the work done by electrical appliances is fixed for each revolution of the watt hour meter, as long as you know the number of turns, you can