If C is any point on the extended line of AB, M is the midpoint of AC, and N is the midpoint of BC, the length of Mn can be obtained So

If C is any point on the extended line of AB, M is the midpoint of AC, and N is the midpoint of BC, the length of Mn can be obtained So

NB=NC=BC/2,MA=MC=AC/2
MN=NA-MA=NB+AB-AC/2=NB+AB-(1/2)(AB+BC)=NB+AB-AB/2-BC/2=AB/2=8/2=4(cm)

2 2
2x -3x-5 -3x -8x+3
And how to do this kind of problem
What is grouping decomposition
What is the addition method

1、 2X ^ 2 - 3x-5 = 2x ^ 2 + 2x-5x-5 (note that + 2x-5x = - 3x is equal to the first term in the original formula) = (2x ^ 2 + 2x) + (- 5x-5) (grouping) = 2x (x + 1) - 5 (x + 1) (grouping decomposition) = (x + 1) (2x-5) (extract the common factor to achieve the purpose of factorization)

The perimeter of the square is 32cm. Can you find the area of the parallelogram?

32 △ 4 = 8 (CM), area: 8 × 8 = 64 (cm 2). Answer: the area of parallelogram is 64 cm 2

1+2=3,1+2+3=6,1+2+3+4=10,1+2+3+4+5=15,1+2+3+4+5+(n+1）=?

There is a formula 1 + 2 + 3 + 4 + 5 + (n + 1) = (1 + N + 1) * (n + 1) / 2, that is, the sum of consecutive numbers is equal to the sum of head and tail multiplied by the number divided by 2

Let the real numbers x1, X2, X3, x4, X5 not be less than 1, and x1 · x2 · x3 · X4 · X5 = 729, then Max {x1x2, x2x3, x3x4, x4x5} is the minimum =?

X1x2 + x3x4 ≥ 2 √ (729 / x5), that is, after taking an X5, x1x2 and x3x4 will not all be less than √ (729 / x5)
x2x3+x4x5 ≥ 2√（792/x1）
√（729/x5）+√（792/x1）≥2√（729*729/x5x1）
If all three inequalities are equal, then
x1x2=x3x4=√（729/x5）
x2x3=x4x5=√（729/x1）
x1=x5
That is, X1 = X3 = X5, X2 = x4, x1x2 = x2x3 = x3x4 = x4x5
So 729 = X1 ^ 3 * x2 ^ 2 = (x1x2) ^ 3 / x2
(x1x2)^3=729*x2
The minimum value of X2 is 1
So the minimum value of x1x2 is 9
In this case, X1 = X3 = X5 = 9, X2 = X4 = 1

The length of the kitchen floor is 45dm and the width is 25dm. How many decimeter square bricks can be used to finish the division? (the side length of the floor tile is required to be the whole decimeter)

The greatest common divisor of 45 and 25 is 5, so it can be finished with square bricks with side length of 5 decimeters

On Kirchhoff's current law
The current flowing into a node is equal to the current flowing out of the node. If the node is an electrical appliance, won't it consume current to do work?
Is the current flowing from the positive pole of the power supply into the negative pole after passing through the load the same as the original current (assuming that there is only one load, power supply positive load negative series mode)?

You understand that there is an error. When the current flows through the consumer, it is not the consumed current, but the consumed electric energy (in other words, when the current flows through the consumer, it is the work done in the consumer, not the consumed). Under the condition that the load parameters of the circuit remain unchanged, the current does not change, and the consumed electric energy is continuously provided by the power supply, In the case of insufficient power (for example, the battery runs out), the current will be reduced

Find the limit (arcsinx / x) ^ (1 / x ^ 2). X approaches 0

How many centimeters is the side length of a large square made of four squares with one centimeter side length

2 cm

Given a = 0.00, etc. 025, B = 0.00, etc. 04, what is the product of a and B?

Infinitely close to 0, can write 0, with 0.9999999999 equal to 1