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1/(x-1)+1/(x-1)(x-2)+1/(x-2)(x-3)+1/(x-3)(x-4)+...+1/(x-99)(x-100)
1/(x-1)+1/(x-1)(x-2)+1/(x-2)(x-3)+1/(x-3)(x-4)+...+1/(x-99)(x-100)
=1/(x-1)+1/(x-2)-1/(x-1)+1/(x-3)-1/(x-2)+.+1/(x-100)-1/(x-99)
=1/(x-100)
（1+2/1)x(1-2/1)x(1+3/1)x(1-3/1)x.x(1+99/10x(x-99/1)
There's something wrong with your question
A rectangle with a circumference of 12 cm (1) the functional relationship between the rectangle s and one side a, and write the value range of the independent variable (2) when a is equal to how long, what is the maximum area of S
Let a be the side length
s=a*(12-a)
s=-a^2 +l2a
Formula:
s=-(a^2-12a+36)+36
s=-(a-6)^2+36
When a = 6, s is the largest and S is 36
Actually, it doesn't count
When the perimeter of the rectangle is fixed, the area of the square is the largest
What is 57 times 67 of 73 plus 67 times 17 of 73?
To process, do not lazy, lazy do not
57 / 73 × 67 + 67 × 17 / 73 = 67 × (57 / 73 + 17 / 73) = 67 × 74 / 73 = 67 × (1 + 1 / 73) = 67 + 67 / 73 = 67 and 67 out of 73. Is that right?
The range of a function is a nonempty set of numbers f (x) = x-3 under the root sign plus 2-x under the root sign
Excuse me for making a mistake
I don't understand. Two questions?
The definition of the function found on Baidu Encyclopedia is as follows:
Function is a kind of correspondence in mathematics, which is the correspondence from nonempty number set a to real number set B. in short, a changes with B, and a is the function of B. to be precise, let X be a nonempty set, y be a nonempty number set, and f be a correspondence rule. If every x in X has a unique element Y corresponding to it according to the correspondence rule F, it is said that the correspondence rule f is a function on X, Denote y = f (x) and call x the domain of function f (x). Set {y | y = f (x), X ∈ r} is its range (the range is a subset of Y). X is called an independent variable and Y is called a dependent variable. Traditionally, y is a function of X. correspondence rule and domain are two elements of function
Note: there are two main points: one is defined on a nonempty real number set and the domain is nonempty; the other is that it should be a simple mapping, that is, for any x, there is only one y corresponding to it
1. The range of a function is a set of nonempty numbers. Yes. If the range is empty, it means that there is no corresponding y for X on the nonempty domain, which does not conform to the second point of the definition of a function;
2. F (x) = x-3 under the root plus 2-x under the root is a function. Wrong. If x-3 under the root plus 2-x under the root wants to be meaningful, it requires x > = 3 and X
If five pieces of square paper with 10 cm side length are overlapped with each other, the perimeter of the figure is 120 cm; if 51 pieces of paper are overlapped like this, the perimeter of the figure is 120 cm（
(2*3+49*2)*10=1040
3, - 3,8, - 8 use four operations to make it equal to 24 (each number can only be used once!)
Good answer
8 /{3-[(-8)/(-3)]}=24
It is known that the sum of the first n terms of the sequence {an} is Sn, and an = Sn * s (n-1) (n is greater than or equal to 2, Sn is not equal to 0), A1 = 2 / 9
(1) Prove: {1 / Sn} is arithmetic sequence
(2) Finding the set of natural numbers n satisfying an > A (n-1)
An = SN-S (n-1) so SN-S (n-1) = Sn * s (n-1) [SN-S (n-1)] / Sn * s (n-1) = 11 / S (n-1) - 1 / Sn = 11 / sn-1 / S (n-1) = - 1, so 1 / Sn is an arithmetic sequence A1 = S11 / S1 = 9 / 21 / sn-1 / S (n-1) = - 1D = - 11 / Sn = 9 / 2 - (n-1) = - N + 11 / 2 = (- 2n + 11) / 2Sn = 2 / (11-2n) an > A (n-1) SN-S (n
The length of the classroom is 8 meters and the width is 6 meters. If the floor is paved with square bricks with a side length of 2 decimeters, how many square bricks do you need? If each square brick costs 2 yuan, how many yuan in total
Classroom area: 8x6 = 48 square meters
2 decimeters = 0.2 meters
48 divided by 0.2 = 240 (blocks)
It costs 240 yuan
240 × 2 = 480 yuan
The total is 480 yuan
Simple operation (2 / 3 + 1 / 2 / 3 / 4) * 1 / 4) (4 - (3 / 4-3 / 8)) * 4 / 29
(2 / 3 + 1 / 2 / 3 / 4) * 1 / 4)
(4 - (3 / 4-3 / 8)) * 4 / 29
These are two simple and quick questions
(2 / 3 + 1 / 2 / 4) × 1 / 4 = (2 / 3 + 1 / 2 × 4 / 3) × 1 / 4 = (2 / 3 + 2 / 3) × 1 / 4 = 4 / 3 × 1 / 4 = 1 / 3 (4 - (3 / 4 - 3 / 8)) * 4 / 29
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