Let n-dimensional vector group A1, A2,..., as, as + 1 (s)

Let n-dimensional vector group A1, A2,..., as, as + 1 (s)

a1,a2...,as,as+1(s

How to solve the equation 2 * (10-2x) / 5 + 5x = 8

2 * (10-2x) / 5 + 5x = 8, both sides multiply by 5 at the same time
2(10-2x)+25x=40
20-4x+25x=40
21x+20=40
21x=40-20
21x=20
x=20/21

If the solution set of inequality m (x-1) > x ^ 2-x about X is {x | 1}

The solution set of ∵ m (x-1) > x2-x is {x | 1 ＜ x ＜ 2},
1,2 are the two roots of the equation m (x-1) = x2-x
Substitute x = 2 to get
m=2

Add an integral to the polynomial x2 + 4 to make it a complete square. The integral that can not satisfy the above conditions is ()
A. 4xB. -4xC. 4D. -4

A. It is a complete square form, so this option is wrong; B, X2 + 4-4x can get x2-4x + 4, can be changed into (X-2) 2; C, X2 + 4 and 4 can get x2 + 8, not a complete square form, so this option is correct; D, X2

Finding the extremum of function f (x) = x-ln (1 + x) with higher numbers

f'(x)=1-1/(1+x)
From F '(x) = 0: x = 0, x > 0, f' (x) > 0, X

Calculating the sum of 1 to 100 in VB

a=0
for i=1 to 100
a=a+i
next i
print a

How many lamps can a meter marked with 220V 2.5A be equipped with at most 220V 40W in normal operation?

The maximum allowable current of 220 V 2.5 a watt hour meter is 2.5 a
Therefore, the maximum allowable power is 220 * 2.5 = 550W
550/40=13.7
In normal operation, it can install up to 13 220V 40W electric lamps

Understanding of zero point theorem
f(1)*f(2)
Graffiti № ayli,

If the function is monotone in the interval [a, b], and f (a) × f (b) ≤ 0
Then the function has at least one zero point in this interval
If the function is monotone in the interval (a, b) and f (a) × f (b)

Calculation of current and power of power line
10 under five, 100 on two, 16, 25 four, 35, 50 three, 70, 95 two and a half times
Through the tube, temperature 8,9 fold, bare wire plus half. Copper upgrade calculation
Take an example, for example, 4 square meters of power cord to do a detailed calculation: how much is the tube, temperature eight or nine, how much is the bare wire plus half? How much is the copper wire upgrade?

You also know this formula! It's very useful, teacher Fu said
4 square aluminum wire as an example: ten under five is less than ten square 4 * 5 = 20A
20 * 0.8 = 16A
Temperature above 40 ℃ 10% 20 * 0.9 = 18a
If it is a bare wire, 20 + 20 * 0.5 = 30A
If it's copper wire, upgrade it from 4 square to 6 square

If √ 5x + 2y-9 and | 2x-6y-7 | are opposite to each other, find the value of X + 1 / y

If the arithmetic square root and absolute value terms are not negative, and the two terms are opposite to each other, then the two terms are equal to 0
5x+2y-9=0 (1)
2x-6y-7=0 (2)
(1)*2-(2)*5
34y=17 y=1/2
Substituting (1)
5x+1-9=0 x=8/5
x+1/y=8/5+2=18/5
x+1/y=18/5