To solve the inequality x-2-1 - a > 0

To solve the inequality x-2-1 - a > 0

When solving this inequality, multiplication and division can be regarded as the same, that is: (X-2) (1-A) > 0, so when a ＜ 1, X ＞ 2, when a ＞ 1, X ＜ 2. Note: a cannot be equal to 1, so there is no need to discuss the case of a = 1

The inequality x ^ 2-x-a (A-1) > 0
What is zero
Why are these two relatively large
(x-a) [x + (A-1)] > 0 is not - A and + (A-1) why should the sign be reversed
Zeros A and - A + 1
Compare size
a>1/2,a>-a+1
a

Zero point is the concept of function, which is the value of the independent variable that makes the function value 0. Note that it is only the independent variable, not the coordinate, that is, the value of X when y = 0 in y = f (x);
(x-a) [x + (A-1)] > 0, to make the left formula zero, x = a or x = - A + 1;
You can draw a simple image of a quadratic function and see where the two zeros are

The odd function f (x) defined in (- 1,1) is a decreasing function if f (1-A) + F (1-3a)

1-A, 1-3a are all in the domain of definition
-1

A problem of space vector in mathematics of senior two
To fill in the blanks today is a cube ABCD-A, B, C, D. It is required to set up an appropriate coordinate system to represent two points on the cube
I'm not the same cube as the answer, the answer is clockwise ABCD, and ABCD is the bottom. But I'm counterclockwise ABCD, and ABCD is the top, so the coordinate system is different. So it's different from the answer
Even if it's a big question, there's only one standard answer,
solve

If the topic requires, is to set up an appropriate coordinate system, used to represent two points on the cube
The answer is not unique
PS: the answer to fill in the blanks is not unique. There is not only one standard answer

Circle O is the inscribed circle of triangle ABC, ∠ ACB = 90 °, ∠ BOC = 105 ° and BC = 20cm, then AC=

O as OE ⊥ BC, of ⊥ AC,
The ecfo is a square,
∵∠BOC=105°
∴∠BOE=105°-45°=60°
∴∠EBO=30°
That is, CBA = 60 degree
∴∠A=30°
∴AB=2BC=40
AC=20√3

Xiaoqiang and Xiaojun have 79 cards in total. Xiaojun's cards are three times less than Xiaoqiang's. how many are there for Xiaojun and Xiaoqiang?

Let Xiaoqiang have X cards, then Xiaojun has (3x-13) cards, then: (3x-13) + x = 79, & nbsp; & nbsp; & nbsp; & nbsp; 3x-13 + x = 79, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 4x-13 = 79, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & x = 23; Xiaojun: 3x-13 = 23 × 3-13 = 56; a: Xiaoqiang has 23 cards, then Xiaojun has 56 cards

Vector a = (3,1), vector b = (- 2,5), then 2A + B equals?

(3x2-2,1x2+5)=(4,7)

In the RT triangle ABC, C = 90 °, BC = 2Mn, AC = M2 - N & # 178;, (M > n > 0), three trigonometric functions of B are obtained

AB = m ^ 2 + n ^ 2, so SINB = (m ^ 2-N ^ 2) / (m ^ 2 + n ^ 2)

Factorization a ^ 4 + A ^ 3 + 6A ^ 2 + 5A + 5
2、4a^4+3a^2+9
3、x^3-5x^2+16
4、x^4+5x^2+15x+9

a^4 a^3 6a^2 5a 5
=（a^4 a^3 a^2） （5a^2 5a 5）
=a^2（a^2 a 1） 5（a^2 a 1）
=（a^2 5）（a^2 a 1）
The key to this kind of problem is to find out the common factor!

As shown in the figure, point F is a focal point of the ellipse x2a2 + y2b2 = 1 (a > b > 0). If there is a point P on the ellipse, the eccentricity of the ellipse is ()
A. 23B. 53C. 22D. 59