If the inequality system x + a ≥ 01 − 2x ＞ x − 2 has a solution, then the value range of a is______ .

If the inequality system x + a ≥ 01 − 2x ＞ x − 2 has a solution, then the value range of a is______ .

∵ from ① we get x ≥ - A, and from ② we get x ＜ 1, so the solution set is - a ≤ x ＜ 1, ∵ a ＜ 1, that is, a ＞ - 1, and the value range of ∵ A is a ＞ - 1. So the answer is: a ＞ - 1
On the inequality system x + 152 ＞ x − 32x + 23 ＜ x + a of X, there are only four integer solutions, then the value range of a is ()
A. -5≤a≤-143B. -5≤a＜-143C. -5＜a≤-143D. -5＜a＜-143
The solution set of inequality system is 2-3a ＜ x ＜ 21, because the inequality system has only four integer solutions, then the four solutions are 20, 19, 18, 17. So we can get 16 ≤ 2-3a ＜ 17, and the solution is - 5 ＜ a ≤ - 143
On the inequality system of X, if two-thirds of X + 15 is greater than x-3 and two-thirds of 2x + 2 is less than x + A, and there are only four integer solutions, then the value range of a?
x/2+15＞x-3;
x+30＞2x-6;
x＜36;
2x/3+2＜x+a;
x/3＞2-a;
x>6-3a;
∴6-3a
If x + 15 is greater than x-3 and 2x + 2 is less than x + A, there are only four integer solutions to find the value of A
(x+15)/2>x-3
(2x+2)/32x-6
X
On the positional relationship between circles
If two equal circles are circumscribed and both are inscribed in a big circle, if the perimeter of the triangle formed by connecting the centers of three circles is 36, what is the radius of the big circle?
Let the radius of the big circle be r, and the radii of the other two circles be a and B respectively
Then the circumference of the triangle (visible in the drawing): (r-a) + (R-B) + (a + b) = 36
R=18
（15-3/X）/4=3X 3X^2-6X+9=4X^2-1
I can't do it
Factorization of 4x square + 20XY + 5Y square
4X square + 20XY + 25y square
=(2x)²+2×2x×5y+(5y)²
=(2x+5y)²
=(2x + radical 5 y) square
A:
4X square + 20XY + 5Y square
=4x²+20xy+5y²
=(2x)²+2×(2x)×5y+(5y)²-20y²
=(2x+5y)²-(2√5y)²
=(2x+5y+2√5y)(2x+5y-2√5y)
=[2x+(5+2√5)y]*[2x+(5-2√5)y]
4X square + 20XY + 25y square
=4x²+20xy+25y²
=(2x+5y)²
The complete set I = R, the set a = x ^ 2 + 2x + a = 0 is not an empty set, B = (x-2010 under X radical is less than or equal to 0), the sum of all elements in a and B may be?
2008,2009,-2
2x-7y = 7x-7y = 7use addition subtraction elimination method to solve equations
Subtraction of two formulas
2x-x=7-7
X=0
0-7y=7
7y=-7
y=-1
If you don't understand this question, you can ask,
2X-7Y=7（1） ，X-7Y=7（2）
The results are as follows
(1) (2) get,
2x-7y-x+7y==7-7
x==0
y==-1
From 1 to 2
2X-7Y-（ X-7Y）=7 -7
2X-7Y- X+7Y=0
X=0
Take x = 0 into 1
2*0-7y=7
-7y=7
-y=1
y=-1
① - 2
X=0
Substitute x = 0 into 2 to get
0-7y=7
-7y=7
y=-1
∴x=0
y=-1
From 1 to 2
2X-7Y-（ X-7Y）=7 -7
2X-7Y- X+7Y=0
X=0
Bring x = 0 in
2*0-7y=7
-7y=7
-y=1
y=-1
The position relationship between line and circle, circle and circle
Line and circle: separation, tangency and intersection
Circle and circle: separated, intersected, circumscribed, inscribed, contained