There are two points m and N on the line ab. point m divides AB into two parts of 2:3, and point n divides AB into two parts of 4:1, and Mn = 3%

There are two points m and N on the line ab. point m divides AB into two parts of 2:3, and point n divides AB into two parts of 4:1, and Mn = 3%

AB is divided into five parts
There are two situations
If M is 2 and N is 4, then AB is 7.5
If M is 2 and N is 1, ab = 15
If M is 3 and N is 4, ab = 15
If M is 3 and N is 1, ab = 7.5
So AB = 7.5 or 15

If M-N = - 2, find the value of M2 + N22 − Mn?

When M-N = - 2, the original formula = M2 − 2Mn + N22 = (m − n) 22 = (− 2) 22 = 2

If the maximum value of y = - X & # 178; - 2x + k is 2, then K=

y=-x²-2x+k
=(x^2-2x+1)+k-1
=(x-1)^2+k-1
≥k-1
There's only a minimum

1. After a 6V rated electric appliance is connected in series with a 4 Ω resistor, it is connected to the power supply and works normally. At this time, the current of the circuit is 0.5A. What is the resistance of the electric appliance and the voltage of the power supply?
2. A lamp connected to a constant voltage power supply has a power of 100W. If the lamp is connected to a long wire and then connected to the same power supply, the power loss of the wire is known to be 9W, then the actual consumption of the lamp is ()
A. 91W B. less than 91W C. more than 91W D. insufficient conditions, unable to determine

1. R = U2 / I = 6V / 0.5A = 12 Ω
Voltage division principle of series circuit 6V / 12 = U1 / 4
U1=2V
U=U1+U2=8V
2.B
Because the wire has resistance, according to P = u ^ 2 / R, the total power of the circuit is less than 100W, and the known wire loss power is 9W, so the actual consumption of the electric lamp is less than 91W

A person is 1.6m tall, standing under the street lamp at night, his shadow is 2m long
If a person is 1.6m tall and stands under a street lamp at night, his shadow is 2m long. When he moves 2m along the direction of the shadow and stands, the shadow length increases by 0.5m. Find the approximate height of the street lamp!

If the lamp height is set as XM, the distance from person to lamp is (2m / 1.6m) xm-2m
Then [(2m / 1.6m) XM + 2.5m] / XM = 2.5m/1.6m
(2m/1.6m)Xm+2.5m=(2.5m/1.6m)Xm
X=8m
The height of street lamp is 8m

As for the electric power of electricity, I hope the process can also be played up
The constant resistance R is connected in series with the sliding rheostat R ', the voltmeter measures the voltage at both ends of R', and the ammeter measures the main circuit current
When sliding rheostat slide P is moved from one position to another, voltmeter indication changes from 8V to 6V, and current indication changes from 0.4A to 0.6A
Calculate the electric power change of the constant resistance R. (regardless of the influence of temperature on the resistance, the power supply voltage is constant)

1. When the slider is in the first position, the voltage of the sliding rheostat is 8V, the current is 0.4A, and the resistance value can be obtained as 20 Ω. When the slider is in the second position, the voltage of the sliding rheostat is 6V, the current is 0.6A, and the resistance value can be obtained as 10 Ω. Set the power supply voltage as U0, the sliding rheostat and the constant resistance in series share the voltage in the first position according to the size of the organization

Spring parameters
Please list the parameters of the spring in detail, what kinds of spring are commonly used in general mold design, and whether the maximum stroke of the spring is the length of maximum tension minus the length of maximum compression?

A. a,d,c,b
B.
b,d,c,a
C. a,c,d,b
D. b,c,d,a
Resistance is a component, inductance is a component, and capacitance is a component
a) Energy consumption b) no energy consumption C) storage of electric field energy d) storage of magnetic field energy

The title of the building owner is not complete. There should be a picture

If there are two objects a and B weighing 1kg and 2kg on a rough plane, and there is a spring in the middle with the original length of 20cm and the stiffness coefficient of 100N per M,
Now use a horizontal pull to pull block B, 2 blocks move at a uniform speed, the distance between 2 blocks is 24cm
Ask about spring force, friction coefficient and horizontal tension
Note that object a is on the left side of B

Elasticity: F = - KX,
=-200*(0.24-0.20)
=-8N
A negative sign indicates that the direction of elasticity is opposite to that of elongation
The force analysis of a shows that the spring tension and friction force are balanced, 8 = μ MAG, μ = 0.8
The force analysis of B shows that f = μ MBG + 8 = 0.8 * 20 + 8 = 24N

In the right triangle ABC, the hypotenuse AC is equal to 4, let the right side AB be equal to x, and the area of the triangle ABC be y, then the function expression of Y with respect to X is, the domain of definition is, and the answer is greater than or equal to 1 and less than or equal to 2. I want to know the specific process,

y=(1/2)*x*[√(4^2-x^2)]
You must be wrong in this domain
Even if the condition of forming a triangle is that both sides are and greater than the third side, x + [√ (4 ^ 2-x ^ 2)] > 4
Plus the number under the root sign is greater than or equal to zero, the combined solution is also 0