There are 8 different books, including 3 Chinese books, 2 mathematics books and 3 other books. If you put these books on the shelf in a row There are 8 different books, including 3 Chinese books, 2 mathematics books and 3 other books. If these books are arranged in a row on the shelf, what is the probability that the Chinese books are not adjacent to each other and the mathematics books are just arranged together? Blank method: first two mathematical binding, as one, and other books 3, a total of 4, a total of 5 spaces, insert 3 Chinese books A53/A88=0.00148

First two mathematical binding, as is 1, and other books 3, a total of 4, a total of 5 spaces, insert 3 language books
A22*A44*A53/A88=1/14

How to say the book on the desk? And how to say "we are at home"?

The book is on the desk.
we stay at home.
I remember what the teacher said

The desk is between the book and the sofa?
It's in English!

The desk is between the sofe and the book.

A & # 178; - 2Ab + B & # 178; + 2A & # 178; + 2ab-b & # 178; merge congeners

a²-2ab+b²+2a²+2ab-b²
=(a²+2a²)+(-2ab+2ab)+(b²-b²)
=3a²

Given the function y = f (x) = x ^ 2-lnx + A, if the minimum value of F (x) is LN2, find the value of A

The derivative of F (x) is 2x-1 / x = (2x ^ 2-1) / X
Because x > 0, we only need to discuss molecules,
When x > root 2 / 2, the function increases monotonically
When 0

Given the function f (x) = ln (E + X / E-X), what is f (a) if f (- a) = - B

It is proved that: (1) because f (x) = e ^ x-ln (x + 1) - 1, f '(x) = e ^ X-1 / (x + 1) and because x ≥ 0, e ^ x ≥ 1 and 0 & lt; 1 / (x + 1) ≤ 1, f' (x) = e ^ X-1 / (x + 1) ≥ 0, the function f (x) = e ^ x-ln (x + 1) - 1 increases monotonically on [0, + ∞), so if x = 0 is the minimum value of function f (x) and the minimum value is f

When a function is seeking a limit, why does the limit not exist?

The nonexistence of limit means that:
1. When the limit is infinite, the limit does not exist
[however, we often write that limf (x) = ∞, even if it is written in this way, it still does not exist]
2. The left and right limits are not equal
[including three cases: one side has limit, one side does not; both sides do not; both sides have, but not equal

The matrix a ∧ 2 = a is known in linear algebra. It is proved that a can be diagonalized

A^2=A;
A(A-E)=0,r(A)+r(A-E)

Do you have any other sizes?

Because size is countable

The planar pad is perpendicular to the planar ABCD, the quadrilateral ABCD is a square, the triangular pad is a right triangle, and PA = ad = 2, e, F, G are line segments PA, PD respectively
The planar pad is perpendicular to the planar ABCD, the quadrilateral ABCD is a square, the triangular pad is a right triangle, and PA = ad = 2, e, F and G are the midpoint of the segments PA, PD and CD respectively. It is proved that Pb is parallel to the planar EFG, and the cosine of the angle between the straight line eg and BD on the different plane is obtained

Take the midpoint of AB as h, connect EH and GH, in △ PAB, eh ‖ Pb, eh in efgh, Pb out of efgh, EFG in ∥ Pb ‖ plane. Connect AG with BD in M, make Mn ‖ eg in ⊿ age and PA in N, then ∠ DMN is obtained. According to the cosine theorem, the cosine value of the angle between eg and BD is √ 3 / 6