What's the purpose of recalling the past when I spent my summer camp in Qingdao in 1983

What's the purpose of recalling the past when I spent my summer camp in Qingdao in 1983

The girl's feeling of crying because of her ignorance is the result of comparing the number of books I have read with the number of 4 million books. After visiting the library of Peking University, she has the same feeling as the girl

When I was 13 years old, why did you say that Peking University was a part of me

Because Peking University has a great influence on the growth of the author, where the author learned a lot, understand a lot!

If the radius of the bottom of a cone is 4cm and the height is 3cm, then the total area of the cone is?

Firstly, the length of the generatrix is calculated. The generatrix length r = √ 4 & # 178; + 3 & # 178; = 5 (CM) is the radius length of the part circle after the cone is expanded
The corresponding circumference of cone is L = 2 π 4 = 8 π
Then the proportion of the corresponding circle to the total circle is h = 8 π / 2 π 5 = 4 / 5
Then the area is 4 / 5 of the total circle
Cone area s = 4 / 5 * π 5 & # 178; = 20 π
Bottom area s. = π R & # 178; = π * 4 & # 178; = 16 π
The total area of this cone is s + S. = 20 π + 16 π = 36 π (CM & # 178;)

Add the appropriate symbol to the left of the equal sign in the following questions to make the result equal to 24
1,4 4 2 4=24
2,2 8 2 4=24

1,4×（ 4 ÷2＋ 4）=24
2,2 ×8＋ 2 ×4=24

Given that the equation of a circle is x ^ 2 + y ^ 2 + 2x-8y + 8 = 0, then the tangent equation of a circle made by passing through point P (2,0) is?

Because the equation is x ^ 2 + y ^ 2 + 2x-8y + 8 = 0, the standard form is (x + 1) ^ 2 + (y-4) ^ 2 = 9, so the center of the circle is (- 1,4), and the radius is r = 3. Let the linear equation passing through point p be y = K (X-2), that is, kx-y-2k = 0. Because the line is tangent to the circle, the distance from the center of the circle to the line = radius 3 = | - k-4-2k | / √ (k ^ 2 + 1) 9 = (3K + 4) ^ 2 / (...)

If A1 (x-1) ∧ 4 + A2 (x-1) ∧ 179; + A3 (x-1) ∧ 178; + A4 (x-1) + A5 = x∧ 4, then what is A2-A3 + A4

Let x = 1, then A5 = 1
Let x = 0, then a1-a2 + a3-a4 + A5 = 0
If the highest order term of X on the left side of the equation is A1 x ^ 4 and x ^ 4 on the right side, then A1 = 1
So A2-A3 + A4 = a1 + A5 = 2

The inequality 5x + 3Y ≤ 15 y ≤ x + 1 x-5y ≤ 3 to find the maximum value of Z = 3x + 5Y should be explained in detail

1. Change inequality into equality
5X+3Y=15 (1)
Y=X+1 (2)
X-5Y=3 (3)
2. By solving the equations, we obtain a (3 / 2,5 / 2), B (- 2, - 1), C (3,0)
They are substituted into Z = 3x + 5Y
ZA=17 ZB=-11 ZC=9
Z = 3x + 5Y max = 17 min = - 11

The reciprocal of one number is 2.4, and the other number is 1 and 3 / 5. What is the sum of the two numbers?

The title seems to be a bit wrong
The first number is 5 / 12, and the second number is 8 / 5
And 121 / 60
If the reciprocal of another number is one and three fifths
And 25 / 24

Solve the equations: 5x + 4Y + Z = 03x + y − 4Z = 11x + y + Z = − 2

5x+4y+z＝0  ①3x+y−4z＝11 ②x+y+z＝−2    ③，②-③，2x-5z=13   ④，③×4-①，4x+4y+4z-5x-4y-z=-2×4，        &nbs...

How to calculate logarithm on calculator
I have a calculation problem here. I don't know how to work it out with a calculator,
200 power of (1 + R) = 2000, find R
It seems that we need to use the logarithm, and then how to calculate it from the calculator is not a problem,

Let's deal with the equation. Let's take the logarithm ln on both sides
have to
200*ln（1+R）=ln（2000)
Then ln (1 + R) = ln (2000) / 200 = ln [(2000) ^ (1 / 200)]
The result is: 1 + r = (2000) ^ (1 / 200) = 1.0387
R=0.0387