How many lamps can be connected to the electric energy meter marked with "220 V, 5A" at most?

The zeros of F (x) = x ^ 3-3x
Proof: the function f (x) = x ^ 3-3x is an increasing function on [1, positive infinity]
Is there a natural number n, f (n) = 1000? If so, find a n that satisfies the condition. If not, explain the reason

f'(x)=3x^2-3
x> When f '(x) > = 1, f' (x) > = 0,
F (x) is an increasing function on [1, positive infinity]
f(10)=1000-301000
And f (x) is an increasing function on [1, positive infinity]
So there is no natural number n such that f (n) = 1000

The words of 600r / kW. H 220 V 5A are marked on a household electric energy meter. How much is the total power allowed to be used?

P=UI=220*5=1100(W)
The total power of electric appliance is not more than 1100W, which has nothing to do with the constant of electric meter 600r / kW. H

(x-3) / 2 = x + (1 / x-1) when sharing, I don't know how to deal with X. how to calculate when x ^ 2 appears?

Multiply both sides of the equation by 2 (x-1) to get (x-1) (x-3) = 2x (x-1) + 2;
x^2-4x+3=2x^2-2x+2
x^2+2x-1=0
Using the formula of quadratic root of two variables, x = [- B ± √ (b ^ 2-4ac)] / 2A
x=-2±√2

The power is supplied to a lamp marked "pz220-60" in a distant construction site by a 220 V power supply. Due to the resistance of the wire, the actual power consumed by the bulb is 55 W. whether the power consumed by the wire is greater than 5 W or less than or equal to 5 W is analyzed and explained by using the learned physical knowledge. It is not calculated, but explained by the formula·

This should have a prerequisite is that the filament resistance is assumed to be constant, and then the resistance can be calculated according to the identification of the bulb, which is r = u square / P = 220 V ＾ 2 / 60 W = 806.7 Ω, and then the voltage of the bulb can be calculated according to the actual power, which is u real = 210.6 V, then the voltage of the wire can be calculated as 9.4 V, and then the passing lamp can be calculated

It is known that the external angles of ∠ B ∠ C in the quadrilateral ABCD are 80 ° 92 ° and ∠ A is 14 ° larger than ∠ D. how many degrees of the internal angles of the quadrilateral?
Because that's why

Because a flat angle is 180 degrees
So ∠ B = 180 ° - 80 ° = 100 °
∠C=180°-92°=88°
And because the sum of the internal angles of the quadrilateral is 360 degrees
Therefore, a + B + C + D = 360 degree
That is: ∠ a + ∠ d = 360 ° - 100 ° - 88 ° = 172 °
Let ∠ d be x, with 2x + 14 ° = 172 °
We get x = 79 degrees
∠A=79°+14°=93° ∠D=79°
There should be no error in the calculation. Let's check it. This is the method

The open circuit voltage is 100V, the short circuit current is 10a, and the load current is several a when the external resistance is 10 ohm

According to Thevenin's theorem, any linear time invariant one port network with source can be replaced equivalently by a voltage source and a series branch of impedance. The voltage of this voltage source is equal to the open circuit voltage of one port network, and this impedance is equal to the input impedance of all independent sources in one port network after being set to zero, When 10 ohm resistance is connected, the load current is 100V / 10 ohm + 10 ohm = 5A

To solve the equation of first degree with one variable,
To transport 600 tons of earth and rock, six A-type cars and four B-type cars can transport the earth and rock five times respectively, or three A-type cars and six B-type cars can transport the earth and rock five times respectively. How many tons can each A-type car and B-type car transport each time?

Suppose that each type a car transports x tons each time, then each type B car transports (600-6 * 5x) / (4 * 5) each time. According to the equation of "3 type a cars, 6 type B cars, respectively transports 5 times, can also be transported completely": 3 * 5x + 6 * 5 * (600-6 * 5x) / (4 * 5) = 600, the value of X can be solved

How long does it take for a 600 Watt appliance to change the battery from 24 V 200 a to 220 V

Regardless of various losses:
The energy consumption is 24 × 200 × 3600 = 17280000j. If the power consumption is 600W, the energy consumption time is 17280000 △ 600 = 28800s = 480min = 8h, 8h
Since the efficiency of the inverter can not be 100% and the actual capacity of the battery is not necessarily the nominal capacity, the actual use time should be shorter than the theoretical calculation time

It is known that the parabola y = x & # 178; - 2x-3 intersects the X axis at two points a and B, and intersects the Y axis at point C
(1) Finding the coordinates of a, B and C
(2) Find the value of s △ ABC
(3) Combined with the image, when x takes what value, Y > 0? What value, y < 0

(1) Let x = 0 give y = - 3
So the coordinates of C are (0, - 3)
Let y = 0 give x = - 1 or x = 3
So the coordinate of a is (- 1,0) and the coordinate of B is (3,0)
（2）S△ABC=1/2*AB*｜OC｜=1/2*4*3=6
(3) When x > 3 or X0
When - 1

How many lamps can be connected to the electric energy meter marked with "220 V, 5A" at most?