1:2000 + 2:2000 + 3:2000 +... + 1999:2000 1 of 55 + 2 of 55 + 3 of 55 +... 10 of 55-11 of 55-12 of 55-13 of 55... - 20 of 55 1-10:1-100:1-1000:1-10000:1-100000:1 1 / 2 + 1 / 3 + 2 / 3 + 1 / 4 + 2 / 4 + 3 / 4 +... + 1 / 60 + 2 / 60 +... 59 / 60

1:2000 + 2:2000 + 3:2000 +... + 1999:2000 1 of 55 + 2 of 55 + 3 of 55 +... 10 of 55-11 of 55-12 of 55-13 of 55... - 20 of 55 1-10:1-100:1-1000:1-10000:1-100000:1 1 / 2 + 1 / 3 + 2 / 3 + 1 / 4 + 2 / 4 + 3 / 4 +... + 1 / 60 + 2 / 60 +... 59 / 60

1:2000 + 2:2000 + 3:2000 +... + 1999:2000
=2000 (1 + 2 + 3 +... + 1999)
=[(1+1999)*1999/2]/2000
=[2000*1999/2]/2000
=1999/2
=999.5
1 of 55 + 2 of 55 + 3 of 55 +... 10 of 55-11 of 55-12 of 55-13 of 55... - 20 of 55
=[(1+10)x10÷2]/55-[(11+20)x10÷2]/55
=[55-31x5]/55
=-100/55
=-20/11
1-10:1-100:1-1000:1-10000:1-100000:1
=100000-100000-100000-100000-1000-100000 100-100000 10-100000 1
=100000 (100000-10000-1000-100-10-1)
=889 out of 100000
=0.88889
1 / 2 + (1 / 3 + 2 / 3) + (1 / 4 + 2 / 4 + 3 / 4) +. + (1 / 60 + 2 / 60 +. + 59 / 60)
=1/2+2/2+3/2+4/2+...+60/2
=(（60+1）×60÷2)/2
=915

English translation
It rained last week, I like rain, cool weather makes people feel very happy!

It was rainy last week.I liked rainy.The weather was cool made me feel very happy!

Given that the sum of the first n terms of {an} is Sn = (2n-1) (n + P), then the real number P =?

If you just want to find P, then it's very simple. The summation formula of arithmetic sequence is expanded, and there is no constant term, P = 0. As a blank or multiple-choice question, it's enough to know this
If you want to find the first item, tolerance and P in detail, write as follows:
Sn=na1+n(n-1)d/2=(d/2)n^2 +(a1 -d/2)n
It is also known that Sn = (2n-1) (n + P) = 2n ^ 2 + (2p-1) n-p
therefore
(d/2)n^2+(a1-d/2)n=2n^2+(2p-1)n -p
(d/2 -2)n^2 +(a1-d/2 -2p +1)n +p=0
If the equality holds for any positive integer n, only
d/2 -2=0
a1- d/2 -2p +1=0
p=0
The solution is A1 = 1, d = 4, P = 0
The general formula an = a1 + (n-1) d = 1 + 4 (n-1) = 4n-3 can also be obtained

If (2x-1) & sup2; + | 3Y + 2 | = 0, then XY=__________ .

The square and absolute value are greater than or equal to 0
The equation holds if both terms are equal to 0
2x-1=0
3y+2=0
x=1/2
y=-2/3
xy=1/2*(-2/3)=-1/3

The carriage of the coal truck is 8m long and 3M wide, and it can load coal up to 12dm high. How many cubic meters of coal can 20 such trucks transport at a time?
If the weight of coal per cubic meter is 1.3 tons, how many tons are there?

12dm=1.2m
8 × 3 × 102 × 20 = 576 M3
576 × 1.3 = 748.8 tons

The logarithm of the maximum vertex angle formed by the intersection of three different lines in the plane is (). A4 B5 C6 D7

Choose D
First check one angle, then check the combined angle of two angles, and finally check the combined angle of three angles
Three, three, one

F (XY) = f (x) + F (y) f (1 / 2) = 1 prove odd function
For the function f (x), the domain of definition is (0, + ∞), f (XY) = f (x) + F (y) and f (1 / 2) = 1, if for 0

f(xy)=f(x)+f(y)
Let x = y = 1, f (1) = f (1) + F (1), so f (1) = 0
F (1 / 2) = 1, so f (1 / 4) = f (1 / 2) + F (1 / 2) = 2
0

What are the main physical properties of water?
From the state, freezing point, boiling point, solubility, conductivity, specific heat and other aspects to describe

Pure water is a colorless, odorless, tasteless, transparent liquid. Pure water is not easy to conduct electricity. Under normal pressure, the freezing point (freezing point) of water is 0 ℃, the boiling point is 100 ℃, at 4 ℃, the mass of 1 cubic centimeter of water is 1g, at this time the density is the largest

Relationship between sound velocity and temperature
The speed of sound propagation in air changes with temperature. Will the speed of sound propagation in solid and liquid change with temperature

It should be, because with the change of temperature, the molecular spacing also changes

.log2^(x+1/x+6)

log2^(x+1/x+6)≤3
The index of two times is the same
x+1/x+6≤8
When x ≠ 0, x + 1 / X ≤ 2
x²-2x+1≤0
The solution is: (x-1) &# 178; ≤ 0
x=1