For the equation (1 + k) x & # 178; + (1 + k) y & # 178; + 4 (k-1) x + 2 (2k-1) y + 4-8k = 0, take any two values of K1 and K2 which are not equal to - 1, whether the curve corresponding to the equation is a circle? If not, explain the reason

For the equation (1 + k) x & # 178; + (1 + k) y & # 178; + 4 (k-1) x + 2 (2k-1) y + 4-8k = 0, take any two values of K1 and K2 which are not equal to - 1, whether the curve corresponding to the equation is a circle? If not, explain the reason

Note: for example, x ^ 2 + y ^ 2 + DX + ey + F = 0
That is, (X-D / 2) ^ 2 + (y-e / 2) ^ 2 = [D ^ 2 + e ^ 2-4f] / 4
When radius r = [D ^ 2 + e ^ 2-4f] / 4 > 0
Then x ^ 2 + y ^ 2 + DX + ey + F = 0 is a circle; otherwise, it is not a circle}
∵k1、k2≠-1 ∴k1+1、k2+1≠0
So x ^ 2 + y ^ 2 + [4 (k-1) x] / (K + 1) + [(4k-2) y] / (K + 1) + (4-8k) / (K + 1) = 0
When {[4 (k-1) / (K + 1)] ^ 2 + [(4k-2) / (K + 1)] ^ 2-4 (4-8k) / (K + 1)} / 4 > 0
Then the curve corresponding to the equation is a circle
The solution is left to the owner
Note: for reference only!

It is known that the equation (A2-1) x2-2 (a + 1) x + 1 = 0 about X has exactly one root, so we can find the value of A

The equation (A2-1) x2-2 (a + 1) x + 1 = 0 has exactly one root
∴a²-1=0,2（a+1)≠0
∴a=±1,a≠-1
∴a=1
One is a quarter

Using multiplication formula to calculate 2013 ^ 2-2013x4024 + 2012 ^ 2

2013^2-2013x4024+2012^2
=2013^2-2×2013x2012+2012^2
=（2013-2012）^2
=1^2
=1

ABCD is a four digit number, and ABCD + AB + a = 2005

abcd+ab+a=2005
Because AB + a > 5
So the thousand bits of ABCD are 1, a = 1
1bcd+1b=2004
After 1 BCD + 1 B, 1 is added to the thousand, so B = 9
19cd+19=2004
19cd=1985
ABCD is 1985

In the brackets below, fill in the number of quarters () number of quarters () number of quarters = one eighth

（1/4+1/4）*1/4

If one side of the matrix equation is 0, can we take determinants for both sides at the same time? For example, ab = 0, | ab | = | 0 |, | a | B | = 0, AB is a square matrix. I think this is wrong, but why not?

X = y means that X and y are the same matrix, so | x | = | y|
It's that simple. The 0 matrix is nothing special

6 + 7.2 = 8.8 8.8 / 2 = 4.4 15.78-4.4 = 11.38 combined into a formula

1.6+7.2+8.8/2+15.78+4.4＝8.8+4.4+11.38
Add left to the left and right to the right, then simplify them

A. Let B be a matrix of the same type, and prove that R (a + b) ≤ R (a) + R (b)
Such as the title
Well, I can tell by thinking about it
Strictly how to prove a class

Just think about it
It's all in standard step shape
Then zero line plus zero line must be zero line
Nonzero lines plus nonzero lines may become zero lines

There is a column of numbers 3, - 6,12, - 24,48 (2) Are there three adjacent numbers whose sum is 2046? If so, please list them
Just answer if it exists and tell me which three numbers it is

a,-2a,4a
a-2a+4a=2046
3a=2046
a=682
The median is - 2 × 682 = - 1364
It has to be a multiple of 6,
And this number is not,
therefore
non-existent.

What is the conversion relationship between feet and inches and our meters and centimeters~

1 foot = 12 inches = 0.3048 meters
1 inch = 2.54 cm