9801 * 99 simple calculation, recursive equation

9801 * 99 simple calculation, recursive equation

9801*99
=9801x（100-1）
=9801x100-9801x1
=980100-9801
=970299

Who can tell me (Shanghai Education Press) ninth grade mathematics (the first semester) practice part of the answer to a problem!
It's from exercise 24.5 (1)
It is known that the ratio of three sides of a triangle is 2:3:4, and the maximum side length of another triangle similar to it is 20 cm, then the other sides of the other triangle are () cm and () cm respectively

Because the ratio of three sides of a triangle is 2:3:4, and the maximum side length of another triangle similar to it is 20 cm, let the three sides of another triangle be 2x: 3x: 4x
4X = 20
x=5
So 2x = 10
3x=15
So the other sides of the triangle are (10) cm and (15) cm long

Is the current price the same as the original price

It's not the same

It is known that the function y = f (x) is defined as R, for any x1, x2
When x is greater than 0, f (x)

This question is a bit troublesome. There are too many small questions, ha ha!
(1) Because it is arbitrary, let x2 = - X1 be substituted to get f (0) = f (x1) + F (- x1). (1)
Let X1 = x2 = 0, then f (0) = f (0) + F (0) solution, f (0) = 0. (2)
Substituting (2) into (1), f (- x1) = - f (x1). So it is an odd function
(2) Because it is an odd function and monotonically decreasing at [0, + infinity) f (n), it is centrosymmetric at the origin, so it is monotonically decreasing at (- infinity, 0)
(3) From (1) (2), we get that x0 is substituted by F (n) = - N, f (- n) = n, f (- n) = - f (n) = n. f (n) = - n
So in the domain, f (n) = - N, monotonically decreasing, so the range is [- m2, - M1]

Solving the equation to find X: a + B = 1 of x-a (B ≠ 1)
(x-a / a) + B = 1 is the problem

a/(x-a) +b =1
a/(x-a)-(b-1)=0
{ a - (b-1)(x-a) } / (x-a) = 0
{ (b-1)x +ab } / (x-a) = 0
(b-1)x +ab = 0
x = ab/(1-b)

A kind of TV set, the original price is 1200 yuan, now the price is 1080 yuan?

(1200-1080) △ 1200, = 120 △ 1200, = 10%; answer: reduce the price by 10%

How to calculate 1 / 1x2 + 1 / 2x3 + 1 / 3x4 + L + 1 / 2004x2005?

My little fresh V,
1/1×2＋1/2×3＋1/3×4＋.＋1/2004×2005
＝1－1/2＋1/2－1/3＋1/3－1/4＋.＋1/2004－1/2005
＝1－1/2005
＝2004/2005

1. There are m seats in the first row of an auditorium, and there are a more seats in the latter row than in the former row. If the total number of seats is n, then the total number of seats is
2. What is the minimum value of the absolute value of X-1 + X-2 + x-3?
3. If the real number a satisfies the absolute value of 1999-a + the absolute value of a-2000 = a, then a-1999 * 1999 (that is, the square of 1999) =?
I'm sorry to trouble you. Let's write down all three questions. The first question is if the total number of rows is n, then what is the total number of digits?

1. Is there something wrong with the first question
2. Minimum 2
When x = 3
When 1 = 3
3. When a2000
a-1999+a-2000=a
a=3999
You can count the rest

If a commodity is sold at 80% of the marked price, it will get a profit of 960 yuan. If it is sold at 80% of the marked price, it will lose 832 yuan compared with the cost price. What is the cost price of this commodity?

(960 + 832) △ 1-80% = 1792 △ 20% = 8960 (yuan) 8960-960 = 8000 (yuan) a: the cost price of this commodity is 8000 yuan

Select six different numbers from 0 to 9 to form a six digit number, which can be divided by 2, 3, 5, 7 and 11. The maximum number is ()
Be careful not to repeat!

986370