(2 of X + 1) (x + 1) (x-1) = necessary process (2a + 1 / 2) (2a-1 / 2) (2 sides of 4A + 1 / 4)= （x+3)(x-3)-2(2-x)(2+x)= (2x+3y)(3x-2y)-(x-2y)(x+2y)= (2-4 of a) (2-5 of a) + (3a + 5) (3a-5)= [(2a-1) (2a + 1) + (a + 2) (A-2) - 4A] (2 of a + 5)=

(2 of X + 1) (x + 1) (x-1) = necessary process (2a + 1 / 2) (2a-1 / 2) (2 sides of 4A + 1 / 4)= （x+3)(x-3)-2(2-x)(2+x)= (2x+3y)(3x-2y)-(x-2y)(x+2y)= (2-4 of a) (2-5 of a) + (3a + 5) (3a-5)= [(2a-1) (2a + 1) + (a + 2) (A-2) - 4A] (2 of a + 5)=

（x^2+1）(x+1)(x-1)
=(x^2+1)(x^2-1)
=x^4-1
(2a+1/2)(2a-1/2)(4a^2+1/4）
=(4a^2-1/4)(4a^2+1/4)
=16a^4-1/16
（x+3)(x-3)-2(2-x)(2+x)
=x^2-9-2(4-x^2)
=x^2-9-8+2x^2
=3x^2-17
(2x+3y)(3x-2y)-(x-2y)(x+2y)
=6x^2+5xy-6y^2-x^2+4y^2
=5x^2+5xy-2y^2
(a^2-4）（a^2-5）+（3a+5)(3a-5）
=a^4-9a^2+20+9a^2-25
=a^4-5
[(2a-1)(2a+1)+(a+2)(a-2)-4a^2]（a^2+5)
=(4a^2-1+a^2-4-4a^2)(a^2+5)
=(a^2-5)(a^2+5)
=a^4-25

In the equal ratio sequence {an}, it is known that A3 = 3 / 2, S3 = 9 / 2 to find A1 and Q

A3 / Q & # 178; + A3 / Q + a3 = S33 / 2 (1 / Q & # 178; + 1 / Q + 1) = 9 / 21 / Q & # 178; + 1 / Q + 1 = 31 / Q & # 178; + 1 / Q - 2 = 0 (1 / Q - 1) (1 / Q + 2) = 0q = 1 or q = - 1 / 2 when q = 1, A1 = 3 / 2 when q = - 1 / 2, A1 = 6

Simple operation of 0.36 * 72 + 36 * 0.28
In 30 minutes!

0.36*72+36*0.28
=0.36*72+0.36*28
=0.36*(72+28)
=0.36*100
=36

For rational number a ` B ` c ` d, a kind of operation is defined: │ a B │ C D = ad BC, such as: 1,0 │ 2, - 2 │ = 1x (- 2) - 0x2 = - 2
If: 3, - 4 (3-x), 5 = 8, find the value of X

:│3,-4│
│（3-x）,5│=8
3x5-(-4)(3-x)=8
15+12-4x=8
4x=19
x=19/4

A family of three adults and four children travel to a certain place. The charge standard of travel agency a is: if you buy four full tickets, the rest will be given half price discount; the charge standard of travel agency B is: family travel is calculated as group ticket, with 75% discount of the original price. The original price of both travel agencies is 100 yuan per person. (1) which travel agency does the family choose cost less? (2) If you join their family tour, which travel agency do you suggest you should go to?

(1) A travel agency: 4 × 100 + 3 × 100 × 50% = 400 + 150, = 550 (yuan); B travel agency: (4 + 3) × 100 × 75% = 7 × 100 × 75%, = 525 (yuan); 525 yuan < 550 yuan, so it costs less to choose B travel agency. A: this family costs less to choose B travel agency. (2) a travel agency

On the congruent diagonalization of matrices
If and only if the algebraic multiplicity is equal to the geometric multiplicity, does the congruent diagonalization of matrices satisfy this theorem

Any symmetric matrix can be congruently diagonalized
two different matters

A is a three digit number and B is a two digit number. If B is placed on the left side of a to form a five digit number, then the five digit number is ()
A. baB. b+aC. 100b+aD. 1000b+a

This five digit number is 1000B + A, so choose D

How to prove that the product of matrix A and matrix A's transpose is 0; and that matrix A and matrix A are zero matrices are necessary and sufficient conditions for each other

If a'a = b = 0, then see the diagonal element B {II} = sum {j from 1 to n} AIJ ^ 2 of B, sum of squares = 0, every term must be 0, so AIJ = 0, so a = 0. On the contrary, it is obviously true

A column of numbers, the first two numbers are 1, 3, starting from the third number, each number is the sum of its first two numbers, that is, 1, 3, 4, 7, 11, 18, 29 Up to the 2006 number, there are______ It's an odd number

This sequence is arranged in the order of "odd, odd and even"; there are two odd numbers and one even number in each group; 2006 △ 3 = 668 (Group) 2; the remainder is 2, both of which are odd; 668 × 2 + 2 = 1338; a: there are 1338 odd numbers

Approximate number 23000, accurate in place, significant number is, with scientific counting method table
Approximate number 23000, accurate in place, significant number is, with scientific counting method table
How should it be written? Why should it be accurate to the hundredth?

The approximate number is 23000, accurate to (hundred) digits, and the significant numbers are 2, 3 and 0, which are expressed as the fourth power of 2.30 × 10 by scientific counting method